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diff --git a/lexers/lexer.lua b/lexers/lexer.lua new file mode 100644 index 0000000..0dc9674 --- /dev/null +++ b/lexers/lexer.lua @@ -0,0 +1,1587 @@ +-- Copyright 2006-2015 Mitchell mitchell.att.foicica.com. See LICENSE. + +local M = {} + +--[=[ This comment is for LuaDoc. +--- +-- Lexes Scintilla documents with Lua and LPeg. +-- +-- ## Overview +-- +-- Lexers highlight the syntax of source code. Scintilla (the editing component +-- behind [Textadept][] and [SciTE][]) traditionally uses static, compiled C++ +-- lexers which are notoriously difficult to create and/or extend. On the other +-- hand, Lua makes it easy to to rapidly create new lexers, extend existing +-- ones, and embed lexers within one another. Lua lexers tend to be more +-- readable than C++ lexers too. +-- +-- Lexers are Parsing Expression Grammars, or PEGs, composed with the Lua +-- [LPeg library][]. The following table comes from the LPeg documentation and +-- summarizes all you need to know about constructing basic LPeg patterns. This +-- module provides convenience functions for creating and working with other +-- more advanced patterns and concepts. +-- +-- Operator | Description +-- ---------------------|------------ +-- `lpeg.P(string)` | Matches `string` literally. +-- `lpeg.P(`_`n`_`)` | Matches exactly _`n`_ characters. +-- `lpeg.S(string)` | Matches any character in set `string`. +-- `lpeg.R("`_`xy`_`")` | Matches any character between range `x` and `y`. +-- `patt^`_`n`_ | Matches at least _`n`_ repetitions of `patt`. +-- `patt^-`_`n`_ | Matches at most _`n`_ repetitions of `patt`. +-- `patt1 * patt2` | Matches `patt1` followed by `patt2`. +-- `patt1 + patt2` | Matches `patt1` or `patt2` (ordered choice). +-- `patt1 - patt2` | Matches `patt1` if `patt2` does not match. +-- `-patt` | Equivalent to `("" - patt)`. +-- `#patt` | Matches `patt` but consumes no input. +-- +-- The first part of this document deals with rapidly constructing a simple +-- lexer. The next part deals with more advanced techniques, such as custom +-- coloring and embedding lexers within one another. Following that is a +-- discussion about code folding, or being able to tell Scintilla which code +-- blocks are "foldable" (temporarily hideable from view). After that are +-- instructions on how to use LPeg lexers with the aforementioned Textadept and +-- SciTE editors. Finally there are comments on lexer performance and +-- limitations. +-- +-- [LPeg library]: http://www.inf.puc-rio.br/~roberto/lpeg/lpeg.html +-- [Textadept]: http://foicica.com/textadept +-- [SciTE]: http://scintilla.org/SciTE.html +-- +-- ## Lexer Basics +-- +-- The *lexers/* directory contains all lexers, including your new one. Before +-- attempting to write one from scratch though, first determine if your +-- programming language is similar to any of the 80+ languages supported. If so, +-- you may be able to copy and modify that lexer, saving some time and effort. +-- The filename of your lexer should be the name of your programming language in +-- lower case followed by a *.lua* extension. For example, a new Lua lexer has +-- the name *lua.lua*. +-- +-- Note: Try to refrain from using one-character language names like "b", "c", +-- or "d". For example, Scintillua uses "b_lang", "cpp", and "dmd", +-- respectively. +-- +-- ### New Lexer Template +-- +-- There is a *lexers/template.txt* file that contains a simple template for a +-- new lexer. Feel free to use it, replacing the '?'s with the name of your +-- lexer: +-- +-- -- ? LPeg lexer. +-- +-- local l = require('lexer') +-- local token, word_match = l.token, l.word_match +-- local P, R, S = lpeg.P, lpeg.R, lpeg.S +-- +-- local M = {_NAME = '?'} +-- +-- -- Whitespace. +-- local ws = token(l.WHITESPACE, l.space^1) +-- +-- M._rules = { +-- {'whitespace', ws}, +-- } +-- +-- M._tokenstyles = { +-- +-- } +-- +-- return M +-- +-- The first 4 lines of code simply define often used convenience variables. The +-- 5th and last lines define and return the lexer object Scintilla uses; they +-- are very important and must be part of every lexer. The sixth line defines +-- something called a "token", an essential building block of lexers. You will +-- learn about tokens shortly. The rest of the code defines a set of grammar +-- rules and token styles. You will learn about those later. Note, however, the +-- `M.` prefix in front of `_rules` and `_tokenstyles`: not only do these tables +-- belong to their respective lexers, but any non-local variables need the `M.` +-- prefix too so-as not to affect Lua's global environment. All in all, this is +-- a minimal, working lexer that you can build on. +-- +-- ### Tokens +-- +-- Take a moment to think about your programming language's structure. What kind +-- of key elements does it have? In the template shown earlier, one predefined +-- element all languages have is whitespace. Your language probably also has +-- elements like comments, strings, and keywords. Lexers refer to these elements +-- as "tokens". Tokens are the fundamental "building blocks" of lexers. Lexers +-- break down source code into tokens for coloring, which results in the syntax +-- highlighting familiar to you. It is up to you how specific your lexer is when +-- it comes to tokens. Perhaps only distinguishing between keywords and +-- identifiers is necessary, or maybe recognizing constants and built-in +-- functions, methods, or libraries is desirable. The Lua lexer, for example, +-- defines 11 tokens: whitespace, comments, strings, numbers, keywords, built-in +-- functions, constants, built-in libraries, identifiers, labels, and operators. +-- Even though constants, built-in functions, and built-in libraries are subsets +-- of identifiers, Lua programmers find it helpful for the lexer to distinguish +-- between them all. It is perfectly acceptable to just recognize keywords and +-- identifiers. +-- +-- In a lexer, tokens consist of a token name and an LPeg pattern that matches a +-- sequence of characters recognized as an instance of that token. Create tokens +-- using the [`lexer.token()`]() function. Let us examine the "whitespace" token +-- defined in the template shown earlier: +-- +-- local ws = token(l.WHITESPACE, l.space^1) +-- +-- At first glance, the first argument does not appear to be a string name and +-- the second argument does not appear to be an LPeg pattern. Perhaps you +-- expected something like: +-- +-- local ws = token('whitespace', S('\t\v\f\n\r ')^1) +-- +-- The `lexer` (`l`) module actually provides a convenient list of common token +-- names and common LPeg patterns for you to use. Token names include +-- [`lexer.DEFAULT`](), [`lexer.WHITESPACE`](), [`lexer.COMMENT`](), +-- [`lexer.STRING`](), [`lexer.NUMBER`](), [`lexer.KEYWORD`](), +-- [`lexer.IDENTIFIER`](), [`lexer.OPERATOR`](), [`lexer.ERROR`](), +-- [`lexer.PREPROCESSOR`](), [`lexer.CONSTANT`](), [`lexer.VARIABLE`](), +-- [`lexer.FUNCTION`](), [`lexer.CLASS`](), [`lexer.TYPE`](), [`lexer.LABEL`](), +-- [`lexer.REGEX`](), and [`lexer.EMBEDDED`](). Patterns include +-- [`lexer.any`](), [`lexer.ascii`](), [`lexer.extend`](), [`lexer.alpha`](), +-- [`lexer.digit`](), [`lexer.alnum`](), [`lexer.lower`](), [`lexer.upper`](), +-- [`lexer.xdigit`](), [`lexer.cntrl`](), [`lexer.graph`](), [`lexer.print`](), +-- [`lexer.punct`](), [`lexer.space`](), [`lexer.newline`](), +-- [`lexer.nonnewline`](), [`lexer.nonnewline_esc`](), [`lexer.dec_num`](), +-- [`lexer.hex_num`](), [`lexer.oct_num`](), [`lexer.integer`](), +-- [`lexer.float`](), and [`lexer.word`](). You may use your own token names if +-- none of the above fit your language, but an advantage to using predefined +-- token names is that your lexer's tokens will inherit the universal syntax +-- highlighting color theme used by your text editor. +-- +-- #### Example Tokens +-- +-- So, how might you define other tokens like comments, strings, and keywords? +-- Here are some examples. +-- +-- **Comments** +-- +-- Line-style comments with a prefix character(s) are easy to express with LPeg: +-- +-- local shell_comment = token(l.COMMENT, '#' * l.nonnewline^0) +-- local c_line_comment = token(l.COMMENT, '//' * l.nonnewline_esc^0) +-- +-- The comments above start with a '#' or "//" and go to the end of the line. +-- The second comment recognizes the next line also as a comment if the current +-- line ends with a '\' escape character. +-- +-- C-style "block" comments with a start and end delimiter are also easy to +-- express: +-- +-- local c_comment = token(l.COMMENT, '/*' * (l.any - '*/')^0 * P('*/')^-1) +-- +-- This comment starts with a "/\*" sequence and contains anything up to and +-- including an ending "\*/" sequence. The ending "\*/" is optional so the lexer +-- can recognize unfinished comments as comments and highlight them properly. +-- +-- **Strings** +-- +-- It is tempting to think that a string is not much different from the block +-- comment shown above in that both have start and end delimiters: +-- +-- local dq_str = '"' * (l.any - '"')^0 * P('"')^-1 +-- local sq_str = "'" * (l.any - "'")^0 * P("'")^-1 +-- local simple_string = token(l.STRING, dq_str + sq_str) +-- +-- However, most programming languages allow escape sequences in strings such +-- that a sequence like "\\"" in a double-quoted string indicates that the +-- '"' is not the end of the string. The above token incorrectly matches +-- such a string. Instead, use the [`lexer.delimited_range()`]() convenience +-- function. +-- +-- local dq_str = l.delimited_range('"') +-- local sq_str = l.delimited_range("'") +-- local string = token(l.STRING, dq_str + sq_str) +-- +-- In this case, the lexer treats '\' as an escape character in a string +-- sequence. +-- +-- **Keywords** +-- +-- Instead of matching _n_ keywords with _n_ `P('keyword_`_`n`_`')` ordered +-- choices, use another convenience function: [`lexer.word_match()`](). It is +-- much easier and more efficient to write word matches like: +-- +-- local keyword = token(l.KEYWORD, l.word_match{ +-- 'keyword_1', 'keyword_2', ..., 'keyword_n' +-- }) +-- +-- local case_insensitive_keyword = token(l.KEYWORD, l.word_match({ +-- 'KEYWORD_1', 'keyword_2', ..., 'KEYword_n' +-- }, nil, true)) +-- +-- local hyphened_keyword = token(l.KEYWORD, l.word_match({ +-- 'keyword-1', 'keyword-2', ..., 'keyword-n' +-- }, '-')) +-- +-- By default, characters considered to be in keywords are in the set of +-- alphanumeric characters and underscores. The last token demonstrates how to +-- allow '-' (hyphen) characters to be in keywords as well. +-- +-- **Numbers** +-- +-- Most programming languages have the same format for integer and float tokens, +-- so it might be as simple as using a couple of predefined LPeg patterns: +-- +-- local number = token(l.NUMBER, l.float + l.integer) +-- +-- However, some languages allow postfix characters on integers. +-- +-- local integer = P('-')^-1 * (l.dec_num * S('lL')^-1) +-- local number = token(l.NUMBER, l.float + l.hex_num + integer) +-- +-- Your language may need other tweaks, but it is up to you how fine-grained you +-- want your highlighting to be. After all, you are not writing a compiler or +-- interpreter! +-- +-- ### Rules +-- +-- Programming languages have grammars, which specify valid token structure. For +-- example, comments usually cannot appear within a string. Grammars consist of +-- rules, which are simply combinations of tokens. Recall from the lexer +-- template the `_rules` table, which defines all the rules used by the lexer +-- grammar: +-- +-- M._rules = { +-- {'whitespace', ws}, +-- } +-- +-- Each entry in a lexer's `_rules` table consists of a rule name and its +-- associated pattern. Rule names are completely arbitrary and serve only to +-- identify and distinguish between different rules. Rule order is important: if +-- text does not match the first rule, the lexer tries the second rule, and so +-- on. This simple grammar says to match whitespace tokens under a rule named +-- "whitespace". +-- +-- To illustrate the importance of rule order, here is an example of a +-- simplified Lua grammar: +-- +-- M._rules = { +-- {'whitespace', ws}, +-- {'keyword', keyword}, +-- {'identifier', identifier}, +-- {'string', string}, +-- {'comment', comment}, +-- {'number', number}, +-- {'label', label}, +-- {'operator', operator}, +-- } +-- +-- Note how identifiers come after keywords. In Lua, as with most programming +-- languages, the characters allowed in keywords and identifiers are in the same +-- set (alphanumerics plus underscores). If the lexer specified the "identifier" +-- rule before the "keyword" rule, all keywords would match identifiers and thus +-- incorrectly highlight as identifiers instead of keywords. The same idea +-- applies to function, constant, etc. tokens that you may want to distinguish +-- between: their rules should come before identifiers. +-- +-- So what about text that does not match any rules? For example in Lua, the '!' +-- character is meaningless outside a string or comment. Normally the lexer +-- skips over such text. If instead you want to highlight these "syntax errors", +-- add an additional end rule: +-- +-- M._rules = { +-- {'whitespace', ws}, +-- {'error', token(l.ERROR, l.any)}, +-- } +-- +-- This identifies and highlights any character not matched by an existing +-- rule as an `lexer.ERROR` token. +-- +-- Even though the rules defined in the examples above contain a single token, +-- rules may consist of multiple tokens. For example, a rule for an HTML tag +-- could consist of a tag token followed by an arbitrary number of attribute +-- tokens, allowing the lexer to highlight all tokens separately. The rule might +-- look something like this: +-- +-- {'tag', tag_start * (ws * attributes)^0 * tag_end^-1} +-- +-- Note however that lexers with complex rules like these are more prone to lose +-- track of their state. +-- +-- ### Summary +-- +-- Lexers primarily consist of tokens and grammar rules. At your disposal are a +-- number of convenience patterns and functions for rapidly creating a lexer. If +-- you choose to use predefined token names for your tokens, you do not have to +-- define how the lexer highlights them. The tokens will inherit the default +-- syntax highlighting color theme your editor uses. +-- +-- ## Advanced Techniques +-- +-- ### Styles and Styling +-- +-- The most basic form of syntax highlighting is assigning different colors to +-- different tokens. Instead of highlighting with just colors, Scintilla allows +-- for more rich highlighting, or "styling", with different fonts, font sizes, +-- font attributes, and foreground and background colors, just to name a few. +-- The unit of this rich highlighting is called a "style". Styles are simply +-- strings of comma-separated property settings. By default, lexers associate +-- predefined token names like `lexer.WHITESPACE`, `lexer.COMMENT`, +-- `lexer.STRING`, etc. with particular styles as part of a universal color +-- theme. These predefined styles include [`lexer.STYLE_CLASS`](), +-- [`lexer.STYLE_COMMENT`](), [`lexer.STYLE_CONSTANT`](), +-- [`lexer.STYLE_ERROR`](), [`lexer.STYLE_EMBEDDED`](), +-- [`lexer.STYLE_FUNCTION`](), [`lexer.STYLE_IDENTIFIER`](), +-- [`lexer.STYLE_KEYWORD`](), [`lexer.STYLE_LABEL`](), [`lexer.STYLE_NUMBER`](), +-- [`lexer.STYLE_OPERATOR`](), [`lexer.STYLE_PREPROCESSOR`](), +-- [`lexer.STYLE_REGEX`](), [`lexer.STYLE_STRING`](), [`lexer.STYLE_TYPE`](), +-- [`lexer.STYLE_VARIABLE`](), and [`lexer.STYLE_WHITESPACE`](). Like with +-- predefined token names and LPeg patterns, you may define your own styles. At +-- their core, styles are just strings, so you may create new ones and/or modify +-- existing ones. Each style consists of the following comma-separated settings: +-- +-- Setting | Description +-- ---------------|------------ +-- font:_name_ | The name of the font the style uses. +-- size:_int_ | The size of the font the style uses. +-- [not]bold | Whether or not the font face is bold. +-- [not]italics | Whether or not the font face is italic. +-- [not]underlined| Whether or not the font face is underlined. +-- fore:_color_ | The foreground color of the font face. +-- back:_color_ | The background color of the font face. +-- [not]eolfilled | Does the background color extend to the end of the line? +-- case:_char_ | The case of the font ('u': upper, 'l': lower, 'm': normal). +-- [not]visible | Whether or not the text is visible. +-- [not]changeable| Whether the text is changeable or read-only. +-- +-- Specify font colors in either "#RRGGBB" format, "0xBBGGRR" format, or the +-- decimal equivalent of the latter. As with token names, LPeg patterns, and +-- styles, there is a set of predefined color names, but they vary depending on +-- the current color theme in use. Therefore, it is generally not a good idea to +-- manually define colors within styles in your lexer since they might not fit +-- into a user's chosen color theme. Try to refrain from even using predefined +-- colors in a style because that color may be theme-specific. Instead, the best +-- practice is to either use predefined styles or derive new color-agnostic +-- styles from predefined ones. For example, Lua "longstring" tokens use the +-- existing `lexer.STYLE_STRING` style instead of defining a new one. +-- +-- #### Example Styles +-- +-- Defining styles is pretty straightforward. An empty style that inherits the +-- default theme settings is simply an empty string: +-- +-- local style_nothing = '' +-- +-- A similar style but with a bold font face looks like this: +-- +-- local style_bold = 'bold' +-- +-- If you want the same style, but also with an italic font face, define the new +-- style in terms of the old one: +-- +-- local style_bold_italic = style_bold..',italics' +-- +-- This allows you to derive new styles from predefined ones without having to +-- rewrite them. This operation leaves the old style unchanged. Thus if you +-- had a "static variable" token whose style you wanted to base off of +-- `lexer.STYLE_VARIABLE`, it would probably look like: +-- +-- local style_static_var = l.STYLE_VARIABLE..',italics' +-- +-- The color theme files in the *lexers/themes/* folder give more examples of +-- style definitions. +-- +-- ### Token Styles +-- +-- Lexers use the `_tokenstyles` table to assign tokens to particular styles. +-- Recall the token definition and `_tokenstyles` table from the lexer template: +-- +-- local ws = token(l.WHITESPACE, l.space^1) +-- +-- ... +-- +-- M._tokenstyles = { +-- +-- } +-- +-- Why is a style not assigned to the `lexer.WHITESPACE` token? As mentioned +-- earlier, lexers automatically associate tokens that use predefined token +-- names with a particular style. Only tokens with custom token names need +-- manual style associations. As an example, consider a custom whitespace token: +-- +-- local ws = token('custom_whitespace', l.space^1) +-- +-- Assigning a style to this token looks like: +-- +-- M._tokenstyles = { +-- custom_whitespace = l.STYLE_WHITESPACE +-- } +-- +-- Do not confuse token names with rule names. They are completely different +-- entities. In the example above, the lexer assigns the "custom_whitespace" +-- token the existing style for `WHITESPACE` tokens. If instead you want to +-- color the background of whitespace a shade of grey, it might look like: +-- +-- local custom_style = l.STYLE_WHITESPACE..',back:$(color.grey)' +-- M._tokenstyles = { +-- custom_whitespace = custom_style +-- } +-- +-- Notice that the lexer peforms Scintilla/SciTE-style "$()" property expansion. +-- You may also use "%()". Remember to refrain from assigning specific colors in +-- styles, but in this case, all user color themes probably define the +-- "color.grey" property. +-- +-- ### Line Lexers +-- +-- By default, lexers match the arbitrary chunks of text passed to them by +-- Scintilla. These chunks may be a full document, only the visible part of a +-- document, or even just portions of lines. Some lexers need to match whole +-- lines. For example, a lexer for the output of a file "diff" needs to know if +-- the line started with a '+' or '-' and then style the entire line +-- accordingly. To indicate that your lexer matches by line, use the +-- `_LEXBYLINE` field: +-- +-- M._LEXBYLINE = true +-- +-- Now the input text for the lexer is a single line at a time. Keep in mind +-- that line lexers do not have the ability to look ahead at subsequent lines. +-- +-- ### Embedded Lexers +-- +-- Lexers embed within one another very easily, requiring minimal effort. In the +-- following sections, the lexer being embedded is called the "child" lexer and +-- the lexer a child is being embedded in is called the "parent". For example, +-- consider an HTML lexer and a CSS lexer. Either lexer stands alone for styling +-- their respective HTML and CSS files. However, CSS can be embedded inside +-- HTML. In this specific case, the CSS lexer is the "child" lexer with the HTML +-- lexer being the "parent". Now consider an HTML lexer and a PHP lexer. This +-- sounds a lot like the case with CSS, but there is a subtle difference: PHP +-- _embeds itself_ into HTML while CSS is _embedded in_ HTML. This fundamental +-- difference results in two types of embedded lexers: a parent lexer that +-- embeds other child lexers in it (like HTML embedding CSS), and a child lexer +-- that embeds itself within a parent lexer (like PHP embedding itself in HTML). +-- +-- #### Parent Lexer +-- +-- Before embedding a child lexer into a parent lexer, the parent lexer needs to +-- load the child lexer. This is done with the [`lexer.load()`]() function. For +-- example, loading the CSS lexer within the HTML lexer looks like: +-- +-- local css = l.load('css') +-- +-- The next part of the embedding process is telling the parent lexer when to +-- switch over to the child lexer and when to switch back. The lexer refers to +-- these indications as the "start rule" and "end rule", respectively, and are +-- just LPeg patterns. Continuing with the HTML/CSS example, the transition from +-- HTML to CSS is when the lexer encounters a "style" tag with a "type" +-- attribute whose value is "text/css": +-- +-- local css_tag = P('<style') * P(function(input, index) +-- if input:find('^[^>]+type="text/css"', index) then +-- return index +-- end +-- end) +-- +-- This pattern looks for the beginning of a "style" tag and searches its +-- attribute list for the text "`type="text/css"`". (In this simplified example, +-- the Lua pattern does not consider whitespace between the '=' nor does it +-- consider that using single quotes is valid.) If there is a match, the +-- functional pattern returns a value instead of `nil`. In this case, the value +-- returned does not matter because we ultimately want to style the "style" tag +-- as an HTML tag, so the actual start rule looks like this: +-- +-- local css_start_rule = #css_tag * tag +-- +-- Now that the parent knows when to switch to the child, it needs to know when +-- to switch back. In the case of HTML/CSS, the switch back occurs when the +-- lexer encounters an ending "style" tag, though the lexer should still style +-- the tag as an HTML tag: +-- +-- local css_end_rule = #P('</style>') * tag +-- +-- Once the parent loads the child lexer and defines the child's start and end +-- rules, it embeds the child with the [`lexer.embed_lexer()`]() function: +-- +-- l.embed_lexer(M, css, css_start_rule, css_end_rule) +-- +-- The first parameter is the parent lexer object to embed the child in, which +-- in this case is `M`. The other three parameters are the child lexer object +-- loaded earlier followed by its start and end rules. +-- +-- #### Child Lexer +-- +-- The process for instructing a child lexer to embed itself into a parent is +-- very similar to embedding a child into a parent: first, load the parent lexer +-- into the child lexer with the [`lexer.load()`]() function and then create +-- start and end rules for the child lexer. However, in this case, swap the +-- lexer object arguments to [`lexer.embed_lexer()`](). For example, in the PHP +-- lexer: +-- +-- local html = l.load('html') +-- local php_start_rule = token('php_tag', '<?php ') +-- local php_end_rule = token('php_tag', '?>') +-- l.embed_lexer(html, M, php_start_rule, php_end_rule) +-- +-- ## Code Folding +-- +-- When reading source code, it is occasionally helpful to temporarily hide +-- blocks of code like functions, classes, comments, etc. This is the concept of +-- "folding". In the Textadept and SciTE editors for example, little indicators +-- in the editor margins appear next to code that can be folded at places called +-- "fold points". When the user clicks an indicator, the editor hides the code +-- associated with the indicator until the user clicks the indicator again. The +-- lexer specifies these fold points and what code exactly to fold. +-- +-- The fold points for most languages occur on keywords or character sequences. +-- Examples of fold keywords are "if" and "end" in Lua and examples of fold +-- character sequences are '{', '}', "/\*", and "\*/" in C for code block and +-- comment delimiters, respectively. However, these fold points cannot occur +-- just anywhere. For example, lexers should not recognize fold keywords that +-- appear within strings or comments. The lexer's `_foldsymbols` table allows +-- you to conveniently define fold points with such granularity. For example, +-- consider C: +-- +-- M._foldsymbols = { +-- [l.OPERATOR] = {['{'] = 1, ['}'] = -1}, +-- [l.COMMENT] = {['/*'] = 1, ['*/'] = -1}, +-- _patterns = {'[{}]', '/%*', '%*/'} +-- } +-- +-- The first assignment states that any '{' or '}' that the lexer recognized as +-- an `lexer.OPERATOR` token is a fold point. The integer `1` indicates the +-- match is a beginning fold point and `-1` indicates the match is an ending +-- fold point. Likewise, the second assignment states that any "/\*" or "\*/" +-- that the lexer recognizes as part of a `lexer.COMMENT` token is a fold point. +-- The lexer does not consider any occurences of these characters outside their +-- defined tokens (such as in a string) as fold points. Finally, every +-- `_foldsymbols` table must have a `_patterns` field that contains a list of +-- [Lua patterns][] that match fold points. If the lexer encounters text that +-- matches one of those patterns, the lexer looks up the matched text in its +-- token's table to determine whether or not the text is a fold point. In the +-- example above, the first Lua pattern matches any '{' or '}' characters. When +-- the lexer comes across one of those characters, it checks if the match is an +-- `lexer.OPERATOR` token. If so, the lexer identifies the match as a fold +-- point. The same idea applies for the other patterns. (The '%' is in the other +-- patterns because '\*' is a special character in Lua patterns that needs +-- escaping.) How do you specify fold keywords? Here is an example for Lua: +-- +-- M._foldsymbols = { +-- [l.KEYWORD] = { +-- ['if'] = 1, ['do'] = 1, ['function'] = 1, +-- ['end'] = -1, ['repeat'] = 1, ['until'] = -1 +-- }, +-- _patterns = {'%l+'} +-- } +-- +-- Any time the lexer encounters a lower case word, if that word is a +-- `lexer.KEYWORD` token and in the associated list of fold points, the lexer +-- identifies the word as a fold point. +-- +-- If your lexer needs to do some additional processing to determine if a match +-- is a fold point, assign a function that returns an integer. Returning `1` or +-- `-1` indicates the match is a fold point. Returning `0` indicates it is not. +-- For example: +-- +-- local function fold_strange_token(text, pos, line, s, match) +-- if ... then +-- return 1 -- beginning fold point +-- elseif ... then +-- return -1 -- ending fold point +-- end +-- return 0 +-- end +-- +-- M._foldsymbols = { +-- ['strange_token'] = {['|'] = fold_strange_token}, +-- _patterns = {'|'} +-- } +-- +-- Any time the lexer encounters a '|' that is a "strange_token", it calls the +-- `fold_strange_token` function to determine if '|' is a fold point. The lexer +-- calls these functions with the following arguments: the text to identify fold +-- points in, the beginning position of the current line in the text to fold, +-- the current line's text, the position in the current line the matched text +-- starts at, and the matched text itself. +-- +-- [Lua patterns]: http://www.lua.org/manual/5.2/manual.html#6.4.1 +-- +-- ### Fold by Indentation +-- +-- Some languages have significant whitespace and/or no delimiters that indicate +-- fold points. If your lexer falls into this category and you would like to +-- mark fold points based on changes in indentation, use the +-- `_FOLDBYINDENTATION` field: +-- +-- M._FOLDBYINDENTATION = true +-- +-- ## Using Lexers +-- +-- ### Textadept +-- +-- Put your lexer in your *~/.textadept/lexers/* directory so you do not +-- overwrite it when upgrading Textadept. Also, lexers in this directory +-- override default lexers. Thus, Textadept loads a user *lua* lexer instead of +-- the default *lua* lexer. This is convenient for tweaking a default lexer to +-- your liking. Then add a [file type][] for your lexer if necessary. +-- +-- [file type]: _M.textadept.file_types.html +-- +-- ### SciTE +-- +-- Create a *.properties* file for your lexer and `import` it in either your +-- *SciTEUser.properties* or *SciTEGlobal.properties*. The contents of the +-- *.properties* file should contain: +-- +-- file.patterns.[lexer_name]=[file_patterns] +-- lexer.$(file.patterns.[lexer_name])=[lexer_name] +-- +-- where `[lexer_name]` is the name of your lexer (minus the *.lua* extension) +-- and `[file_patterns]` is a set of file extensions to use your lexer for. +-- +-- Please note that Lua lexers ignore any styling information in *.properties* +-- files. Your theme file in the *lexers/themes/* directory contains styling +-- information. +-- +-- ## Considerations +-- +-- ### Performance +-- +-- There might be some slight overhead when initializing a lexer, but loading a +-- file from disk into Scintilla is usually more expensive. On modern computer +-- systems, I see no difference in speed between LPeg lexers and Scintilla's C++ +-- ones. Optimize lexers for speed by re-arranging rules in the `_rules` table +-- so that the most common rules match first. Do keep in mind that order matters +-- for similar rules. +-- +-- ### Limitations +-- +-- Embedded preprocessor languages like PHP cannot completely embed in their +-- parent languages in that the parent's tokens do not support start and end +-- rules. This mostly goes unnoticed, but code like +-- +-- <div id="<?php echo $id; ?>"> +-- +-- or +-- +-- <div <?php if ($odd) { echo 'class="odd"'; } ?>> +-- +-- will not style correctly. +-- +-- ### Troubleshooting +-- +-- Errors in lexers can be tricky to debug. Lexers print Lua errors to +-- `io.stderr` and `_G.print()` statements to `io.stdout`. Running your editor +-- from a terminal is the easiest way to see errors as they occur. +-- +-- ### Risks +-- +-- Poorly written lexers have the ability to crash Scintilla (and thus its +-- containing application), so unsaved data might be lost. However, I have only +-- observed these crashes in early lexer development, when syntax errors or +-- pattern errors are present. Once the lexer actually starts styling text +-- (either correctly or incorrectly, it does not matter), I have not observed +-- any crashes. +-- +-- ### Acknowledgements +-- +-- Thanks to Peter Odding for his [lexer post][] on the Lua mailing list +-- that inspired me, and thanks to Roberto Ierusalimschy for LPeg. +-- +-- [lexer post]: http://lua-users.org/lists/lua-l/2007-04/msg00116.html +-- @field LEXERPATH (string) +-- The path used to search for a lexer to load. +-- Identical in format to Lua's `package.path` string. +-- The default value is `package.path`. +-- @field DEFAULT (string) +-- The token name for default tokens. +-- @field WHITESPACE (string) +-- The token name for whitespace tokens. +-- @field COMMENT (string) +-- The token name for comment tokens. +-- @field STRING (string) +-- The token name for string tokens. +-- @field NUMBER (string) +-- The token name for number tokens. +-- @field KEYWORD (string) +-- The token name for keyword tokens. +-- @field IDENTIFIER (string) +-- The token name for identifier tokens. +-- @field OPERATOR (string) +-- The token name for operator tokens. +-- @field ERROR (string) +-- The token name for error tokens. +-- @field PREPROCESSOR (string) +-- The token name for preprocessor tokens. +-- @field CONSTANT (string) +-- The token name for constant tokens. +-- @field VARIABLE (string) +-- The token name for variable tokens. +-- @field FUNCTION (string) +-- The token name for function tokens. +-- @field CLASS (string) +-- The token name for class tokens. +-- @field TYPE (string) +-- The token name for type tokens. +-- @field LABEL (string) +-- The token name for label tokens. +-- @field REGEX (string) +-- The token name for regex tokens. +-- @field STYLE_CLASS (string) +-- The style typically used for class definitions. +-- @field STYLE_COMMENT (string) +-- The style typically used for code comments. +-- @field STYLE_CONSTANT (string) +-- The style typically used for constants. +-- @field STYLE_ERROR (string) +-- The style typically used for erroneous syntax. +-- @field STYLE_FUNCTION (string) +-- The style typically used for function definitions. +-- @field STYLE_KEYWORD (string) +-- The style typically used for language keywords. +-- @field STYLE_LABEL (string) +-- The style typically used for labels. +-- @field STYLE_NUMBER (string) +-- The style typically used for numbers. +-- @field STYLE_OPERATOR (string) +-- The style typically used for operators. +-- @field STYLE_REGEX (string) +-- The style typically used for regular expression strings. +-- @field STYLE_STRING (string) +-- The style typically used for strings. +-- @field STYLE_PREPROCESSOR (string) +-- The style typically used for preprocessor statements. +-- @field STYLE_TYPE (string) +-- The style typically used for static types. +-- @field STYLE_VARIABLE (string) +-- The style typically used for variables. +-- @field STYLE_WHITESPACE (string) +-- The style typically used for whitespace. +-- @field STYLE_EMBEDDED (string) +-- The style typically used for embedded code. +-- @field STYLE_IDENTIFIER (string) +-- The style typically used for identifier words. +-- @field STYLE_DEFAULT (string) +-- The style all styles are based off of. +-- @field STYLE_LINENUMBER (string) +-- The style used for all margins except fold margins. +-- @field STYLE_BRACELIGHT (string) +-- The style used for highlighted brace characters. +-- @field STYLE_BRACEBAD (string) +-- The style used for unmatched brace characters. +-- @field STYLE_CONTROLCHAR (string) +-- The style used for control characters. +-- Color attributes are ignored. +-- @field STYLE_INDENTGUIDE (string) +-- The style used for indentation guides. +-- @field STYLE_CALLTIP (string) +-- The style used by call tips if [`buffer.call_tip_use_style`]() is set. +-- Only the font name, size, and color attributes are used. +-- @field any (pattern) +-- A pattern that matches any single character. +-- @field ascii (pattern) +-- A pattern that matches any ASCII character (codes 0 to 127). +-- @field extend (pattern) +-- A pattern that matches any ASCII extended character (codes 0 to 255). +-- @field alpha (pattern) +-- A pattern that matches any alphabetic character ('A'-'Z', 'a'-'z'). +-- @field digit (pattern) +-- A pattern that matches any digit ('0'-'9'). +-- @field alnum (pattern) +-- A pattern that matches any alphanumeric character ('A'-'Z', 'a'-'z', +-- '0'-'9'). +-- @field lower (pattern) +-- A pattern that matches any lower case character ('a'-'z'). +-- @field upper (pattern) +-- A pattern that matches any upper case character ('A'-'Z'). +-- @field xdigit (pattern) +-- A pattern that matches any hexadecimal digit ('0'-'9', 'A'-'F', 'a'-'f'). +-- @field cntrl (pattern) +-- A pattern that matches any control character (ASCII codes 0 to 31). +-- @field graph (pattern) +-- A pattern that matches any graphical character ('!' to '~'). +-- @field print (pattern) +-- A pattern that matches any printable character (' ' to '~'). +-- @field punct (pattern) +-- A pattern that matches any punctuation character ('!' to '/', ':' to '@', +-- '[' to ''', '{' to '~'). +-- @field space (pattern) +-- A pattern that matches any whitespace character ('\t', '\v', '\f', '\n', +-- '\r', space). +-- @field newline (pattern) +-- A pattern that matches any set of end of line characters. +-- @field nonnewline (pattern) +-- A pattern that matches any single, non-newline character. +-- @field nonnewline_esc (pattern) +-- A pattern that matches any single, non-newline character or any set of end +-- of line characters escaped with '\'. +-- @field dec_num (pattern) +-- A pattern that matches a decimal number. +-- @field hex_num (pattern) +-- A pattern that matches a hexadecimal number. +-- @field oct_num (pattern) +-- A pattern that matches an octal number. +-- @field integer (pattern) +-- A pattern that matches either a decimal, hexadecimal, or octal number. +-- @field float (pattern) +-- A pattern that matches a floating point number. +-- @field word (pattern) +-- A pattern that matches a typical word. Words begin with a letter or +-- underscore and consist of alphanumeric and underscore characters. +-- @field FOLD_BASE (number) +-- The initial (root) fold level. +-- @field FOLD_BLANK (number) +-- Flag indicating that the line is blank. +-- @field FOLD_HEADER (number) +-- Flag indicating the line is fold point. +-- @field fold_level (table, Read-only) +-- Table of fold level bit-masks for line numbers starting from zero. +-- Fold level masks are composed of an integer level combined with any of the +-- following bits: +-- +-- * `lexer.FOLD_BASE` +-- The initial fold level. +-- * `lexer.FOLD_BLANK` +-- The line is blank. +-- * `lexer.FOLD_HEADER` +-- The line is a header, or fold point. +-- @field indent_amount (table, Read-only) +-- Table of indentation amounts in character columns, for line numbers +-- starting from zero. +-- @field property (table) +-- Map of key-value string pairs. +-- @field property_expanded (table, Read-only) +-- Map of key-value string pairs with `$()` and `%()` variable replacement +-- performed in values. +-- @field property_int (table, Read-only) +-- Map of key-value pairs with values interpreted as numbers, or `0` if not +-- found. +-- @field style_at (table, Read-only) +-- Table of style names at positions in the buffer starting from zero. +module('lexer')]=] + +local lpeg = require('lpeg') +local lpeg_P, lpeg_R, lpeg_S, lpeg_V = lpeg.P, lpeg.R, lpeg.S, lpeg.V +local lpeg_Ct, lpeg_Cc, lpeg_Cp = lpeg.Ct, lpeg.Cc, lpeg.Cp +local lpeg_Cmt, lpeg_C = lpeg.Cmt, lpeg.C +local lpeg_match = lpeg.match + +M.LEXERPATH = package.path + +-- Table of loaded lexers. +local lexers = {} + +-- Keep track of the last parent lexer loaded. This lexer's rules are used for +-- proxy lexers (those that load parent and child lexers to embed) that do not +-- declare a parent lexer. +local parent_lexer + +if not package.searchpath then + -- Searches for the given *name* in the given *path*. + -- This is an implementation of Lua 5.2's `package.searchpath()` function for + -- Lua 5.1. + function package.searchpath(name, path) + local tried = {} + for part in path:gmatch('[^;]+') do + local filename = part:gsub('%?', name) + local f = io.open(filename, 'r') + if f then f:close() return filename end + tried[#tried + 1] = ("no file '%s'"):format(filename) + end + return nil, table.concat(tried, '\n') + end +end + +-- Adds a rule to a lexer's current ordered list of rules. +-- @param lexer The lexer to add the given rule to. +-- @param name The name associated with this rule. It is used for other lexers +-- to access this particular rule from the lexer's `_RULES` table. It does not +-- have to be the same as the name passed to `token`. +-- @param rule The LPeg pattern of the rule. +local function add_rule(lexer, id, rule) + if not lexer._RULES then + lexer._RULES = {} + -- Contains an ordered list (by numerical index) of rule names. This is used + -- in conjunction with lexer._RULES for building _TOKENRULE. + lexer._RULEORDER = {} + end + lexer._RULES[id] = rule + lexer._RULEORDER[#lexer._RULEORDER + 1] = id +end + +-- Adds a new Scintilla style to Scintilla. +-- @param lexer The lexer to add the given style to. +-- @param token_name The name of the token associated with this style. +-- @param style A Scintilla style created from `style()`. +-- @see style +local function add_style(lexer, token_name, style) + local num_styles = lexer._numstyles + if num_styles == 32 then num_styles = num_styles + 8 end -- skip predefined + if num_styles >= 255 then print('Too many styles defined (255 MAX)') end + lexer._TOKENSTYLES[token_name], lexer._numstyles = num_styles, num_styles + 1 + lexer._EXTRASTYLES[token_name] = style +end + +-- (Re)constructs `lexer._TOKENRULE`. +-- @param parent The parent lexer. +local function join_tokens(lexer) + local patterns, order = lexer._RULES, lexer._RULEORDER + local token_rule = patterns[order[1]] + for i = 2, #order do token_rule = token_rule + patterns[order[i]] end + lexer._TOKENRULE = token_rule + M.token(M.DEFAULT, M.any) + return lexer._TOKENRULE +end + +-- Adds a given lexer and any of its embedded lexers to a given grammar. +-- @param grammar The grammar to add the lexer to. +-- @param lexer The lexer to add. +local function add_lexer(grammar, lexer, token_rule) + local token_rule = join_tokens(lexer) + local lexer_name = lexer._NAME + for _, child in ipairs(lexer._CHILDREN) do + if child._CHILDREN then add_lexer(grammar, child) end + local child_name = child._NAME + local rules = child._EMBEDDEDRULES[lexer_name] + local rules_token_rule = grammar['__'..child_name] or rules.token_rule + grammar[child_name] = (-rules.end_rule * rules_token_rule)^0 * + rules.end_rule^-1 * lpeg_V(lexer_name) + local embedded_child = '_'..child_name + grammar[embedded_child] = rules.start_rule * (-rules.end_rule * + rules_token_rule)^0 * rules.end_rule^-1 + token_rule = lpeg_V(embedded_child) + token_rule + end + grammar['__'..lexer_name] = token_rule -- can contain embedded lexer rules + grammar[lexer_name] = token_rule^0 +end + +-- (Re)constructs `lexer._GRAMMAR`. +-- @param lexer The parent lexer. +-- @param initial_rule The name of the rule to start lexing with. The default +-- value is `lexer._NAME`. Multilang lexers use this to start with a child +-- rule if necessary. +local function build_grammar(lexer, initial_rule) + local children = lexer._CHILDREN + if children then + local lexer_name = lexer._NAME + if not initial_rule then initial_rule = lexer_name end + local grammar = {initial_rule} + add_lexer(grammar, lexer) + lexer._INITIALRULE = initial_rule + lexer._GRAMMAR = lpeg_Ct(lpeg_P(grammar)) + else + lexer._GRAMMAR = lpeg_Ct(join_tokens(lexer)^0) + end +end + +local string_upper = string.upper +-- Default styles. +local default = { + 'nothing', 'whitespace', 'comment', 'string', 'number', 'keyword', + 'identifier', 'operator', 'error', 'preprocessor', 'constant', 'variable', + 'function', 'class', 'type', 'label', 'regex', 'embedded' +} +for _, v in ipairs(default) do + M[string_upper(v)], M['STYLE_'..string_upper(v)] = v, '$(style.'..v..')' +end +-- Predefined styles. +local predefined = { + 'default', 'linenumber', 'bracelight', 'bracebad', 'controlchar', + 'indentguide', 'calltip' +} +for _, v in ipairs(predefined) do + M[string_upper(v)], M['STYLE_'..string_upper(v)] = v, '$(style.'..v..')' +end + +--- +-- Initializes or loads and returns the lexer of string name *name*. +-- Scintilla calls this function to load a lexer. Parent lexers also call this +-- function to load child lexers and vice-versa. The user calls this function +-- to load a lexer when using Scintillua as a Lua library. +-- @param name The name of the lexing language. +-- @param alt_name The alternate name of the lexing language. This is useful for +-- embedding the same child lexer with multiple sets of start and end tokens. +-- @return lexer object +-- @name load +function M.load(name, alt_name) + if lexers[alt_name or name] then return lexers[alt_name or name] end + parent_lexer = nil -- reset + + -- When using Scintillua as a stand-alone module, the `property` and + -- `property_int` tables do not exist (they are not useful). Create them to + -- prevent errors from occurring. + if not M.property then + M.property, M.property_int = {}, setmetatable({}, { + __index = function(t, k) + return tostring(tonumber(M.property[k]) or 0) + end, + __newindex = function() error('read-only property') end + }) + end + + -- Load the language lexer with its rules, styles, etc. + M.WHITESPACE = (alt_name or name)..'_whitespace' + local lexer_file, error = package.searchpath(name, M.LEXERPATH) + local ok, lexer = pcall(dofile, lexer_file or '') + if not ok then + _G.print(error or lexer) -- error message + lexer = {_NAME = alt_name or name} + end + if alt_name then lexer._NAME = alt_name end + + -- Create the initial maps for token names to style numbers and styles. + local token_styles = {} + for i = 1, #default do token_styles[default[i]] = i - 1 end + for i = 1, #predefined do token_styles[predefined[i]] = i + 31 end + lexer._TOKENSTYLES, lexer._numstyles = token_styles, #default + lexer._EXTRASTYLES = {} + + -- If the lexer is a proxy (loads parent and child lexers to embed) and does + -- not declare a parent, try and find one and use its rules. + if not lexer._rules and not lexer._lexer then lexer._lexer = parent_lexer end + + -- If the lexer is a proxy or a child that embedded itself, add its rules and + -- styles to the parent lexer. Then set the parent to be the main lexer. + if lexer._lexer then + local l, _r, _s = lexer._lexer, lexer._rules, lexer._tokenstyles + if not l._tokenstyles then l._tokenstyles = {} end + for _, r in ipairs(_r or {}) do + -- Prevent rule id clashes. + l._rules[#l._rules + 1] = {lexer._NAME..'_'..r[1], r[2]} + end + for token, style in pairs(_s or {}) do l._tokenstyles[token] = style end + lexer = l + end + + -- Add the lexer's styles and build its grammar. + if lexer._rules then + for token, style in pairs(lexer._tokenstyles or {}) do + add_style(lexer, token, style) + end + for _, r in ipairs(lexer._rules) do add_rule(lexer, r[1], r[2]) end + build_grammar(lexer) + end + -- Add the lexer's unique whitespace style. + add_style(lexer, lexer._NAME..'_whitespace', M.STYLE_WHITESPACE) + + -- Process the lexer's fold symbols. + if lexer._foldsymbols and lexer._foldsymbols._patterns then + local patterns = lexer._foldsymbols._patterns + for i = 1, #patterns do patterns[i] = '()('..patterns[i]..')' end + end + + lexer.lex, lexer.fold = M.lex, M.fold + lexers[alt_name or name] = lexer + return lexer +end + +--- +-- Lexes a chunk of text *text* (that has an initial style number of +-- *init_style*) with lexer *lexer*. +-- If *lexer* has a `_LEXBYLINE` flag set, the text is lexed one line at a time. +-- Otherwise the text is lexed as a whole. +-- @param lexer The lexer object to lex with. +-- @param text The text in the buffer to lex. +-- @param init_style The current style. Multiple-language lexers use this to +-- determine which language to start lexing in. +-- @return table of token names and positions. +-- @name lex +function M.lex(lexer, text, init_style) + if not lexer._LEXBYLINE then + -- For multilang lexers, build a new grammar whose initial_rule is the + -- current language. + if lexer._CHILDREN then + for style, style_num in pairs(lexer._TOKENSTYLES) do + if style_num == init_style then + local lexer_name = style:match('^(.+)_whitespace') or lexer._NAME + if lexer._INITIALRULE ~= lexer_name then + build_grammar(lexer, lexer_name) + end + break + end + end + end + return lpeg_match(lexer._GRAMMAR, text) + else + local tokens = {} + local function append(tokens, line_tokens, offset) + for i = 1, #line_tokens, 2 do + tokens[#tokens + 1] = line_tokens[i] + tokens[#tokens + 1] = line_tokens[i + 1] + offset + end + end + local offset = 0 + local grammar = lexer._GRAMMAR + for line in text:gmatch('[^\r\n]*\r?\n?') do + local line_tokens = lpeg_match(grammar, line) + if line_tokens then append(tokens, line_tokens, offset) end + offset = offset + #line + -- Use the default style to the end of the line if none was specified. + if tokens[#tokens] ~= offset then + tokens[#tokens + 1], tokens[#tokens + 2] = 'default', offset + 1 + end + end + return tokens + end +end + +--- +-- Folds a chunk of text *text* with lexer *lexer*. +-- Folds *text* starting at position *start_pos* on line number *start_line* +-- with a beginning fold level of *start_level* in the buffer. If *lexer* has a +-- a `_fold` function or a `_foldsymbols` table, that field is used to perform +-- folding. Otherwise, if *lexer* has a `_FOLDBYINDENTATION` field set, or if a +-- `fold.by.indentation` property is set, folding by indentation is done. +-- @param lexer The lexer object to fold with. +-- @param text The text in the buffer to fold. +-- @param start_pos The position in the buffer *text* starts at. +-- @param start_line The line number *text* starts on. +-- @param start_level The fold level *text* starts on. +-- @return table of fold levels. +-- @name fold +function M.fold(lexer, text, start_pos, start_line, start_level) + local folds = {} + if text == '' then return folds end + local fold = M.property_int['fold'] > 0 + local FOLD_BASE = M.FOLD_BASE + local FOLD_HEADER, FOLD_BLANK = M.FOLD_HEADER, M.FOLD_BLANK + if fold and lexer._fold then + return lexer._fold(text, start_pos, start_line, start_level) + elseif fold and lexer._foldsymbols then + local lines = {} + for p, l in (text..'\n'):gmatch('()(.-)\r?\n') do + lines[#lines + 1] = {p, l} + end + local fold_zero_sum_lines = M.property_int['fold.on.zero.sum.lines'] > 0 + local fold_symbols = lexer._foldsymbols + local fold_symbols_patterns = fold_symbols._patterns + local style_at, fold_level = M.style_at, M.fold_level + local line_num, prev_level = start_line, start_level + local current_level = prev_level + for i = 1, #lines do + local pos, line = lines[i][1], lines[i][2] + if line ~= '' then + local level_decreased = false + for j = 1, #fold_symbols_patterns do + for s, match in line:gmatch(fold_symbols_patterns[j]) do + local symbols = fold_symbols[style_at[start_pos + pos + s - 1]] + local l = symbols and symbols[match] + if type(l) == 'function' then l = l(text, pos, line, s, match) end + if type(l) == 'number' then + current_level = current_level + l + if l < 0 and current_level < prev_level then + -- Potential zero-sum line. If the level were to go back up on + -- the same line, the line may be marked as a fold header. + level_decreased = true + end + end + end + end + folds[line_num] = prev_level + if current_level > prev_level then + folds[line_num] = prev_level + FOLD_HEADER + elseif level_decreased and current_level == prev_level and + fold_zero_sum_lines then + if line_num > start_line then + folds[line_num] = prev_level - 1 + FOLD_HEADER + else + -- Typing within a zero-sum line. + local level = fold_level[line_num - 1] - 1 + if level > FOLD_HEADER then level = level - FOLD_HEADER end + if level > FOLD_BLANK then level = level - FOLD_BLANK end + folds[line_num] = level + FOLD_HEADER + current_level = current_level + 1 + end + end + if current_level < FOLD_BASE then current_level = FOLD_BASE end + prev_level = current_level + else + folds[line_num] = prev_level + FOLD_BLANK + end + line_num = line_num + 1 + end + elseif fold and (lexer._FOLDBYINDENTATION or + M.property_int['fold.by.indentation'] > 0) then + -- Indentation based folding. + -- Calculate indentation per line. + local indentation = {} + for indent, line in (text..'\n'):gmatch('([\t ]*)([^\r\n]*)\r?\n') do + indentation[#indentation + 1] = line ~= '' and #indent + end + -- Find the first non-blank line before start_line. If the current line is + -- indented, make that previous line a header and update the levels of any + -- blank lines inbetween. If the current line is blank, match the level of + -- the previous non-blank line. + local current_level = start_level + for i = start_line - 1, 0, -1 do + local level = M.fold_level[i] + if level >= FOLD_HEADER then level = level - FOLD_HEADER end + if level < FOLD_BLANK then + local indent = M.indent_amount[i] + if indentation[1] and indentation[1] > indent then + folds[i] = FOLD_BASE + indent + FOLD_HEADER + for j = i + 1, start_line - 1 do + folds[j] = start_level + FOLD_BLANK + end + elseif not indentation[1] then + current_level = FOLD_BASE + indent + end + break + end + end + -- Iterate over lines, setting fold numbers and fold flags. + for i = 1, #indentation do + if indentation[i] then + current_level = FOLD_BASE + indentation[i] + folds[start_line + i - 1] = current_level + for j = i + 1, #indentation do + if indentation[j] then + if FOLD_BASE + indentation[j] > current_level then + folds[start_line + i - 1] = current_level + FOLD_HEADER + current_level = FOLD_BASE + indentation[j] -- for any blanks below + end + break + end + end + else + folds[start_line + i - 1] = current_level + FOLD_BLANK + end + end + else + -- No folding, reset fold levels if necessary. + local current_line = start_line + for _ in text:gmatch('\r?\n') do + folds[current_line] = start_level + current_line = current_line + 1 + end + end + return folds +end + +-- The following are utility functions lexers will have access to. + +-- Common patterns. +M.any = lpeg_P(1) +M.ascii = lpeg_R('\000\127') +M.extend = lpeg_R('\000\255') +M.alpha = lpeg_R('AZ', 'az') +M.digit = lpeg_R('09') +M.alnum = lpeg_R('AZ', 'az', '09') +M.lower = lpeg_R('az') +M.upper = lpeg_R('AZ') +M.xdigit = lpeg_R('09', 'AF', 'af') +M.cntrl = lpeg_R('\000\031') +M.graph = lpeg_R('!~') +M.print = lpeg_R(' ~') +M.punct = lpeg_R('!/', ':@', '[\'', '{~') +M.space = lpeg_S('\t\v\f\n\r ') + +M.newline = lpeg_S('\r\n\f')^1 +M.nonnewline = 1 - M.newline +M.nonnewline_esc = 1 - (M.newline + '\\') + '\\' * M.any + +M.dec_num = M.digit^1 +M.hex_num = '0' * lpeg_S('xX') * M.xdigit^1 +M.oct_num = '0' * lpeg_R('07')^1 +M.integer = lpeg_S('+-')^-1 * (M.hex_num + M.oct_num + M.dec_num) +M.float = lpeg_S('+-')^-1 * + (M.digit^0 * '.' * M.digit^1 + M.digit^1 * '.' * M.digit^0 + + M.digit^1) * + lpeg_S('eE') * lpeg_S('+-')^-1 * M.digit^1 +M.word = (M.alpha + '_') * (M.alnum + '_')^0 + +--- +-- Creates and returns a token pattern with token name *name* and pattern +-- *patt*. +-- If *name* is not a predefined token name, its style must be defined in the +-- lexer's `_tokenstyles` table. +-- @param name The name of token. If this name is not a predefined token name, +-- then a style needs to be assiciated with it in the lexer's `_tokenstyles` +-- table. +-- @param patt The LPeg pattern associated with the token. +-- @return pattern +-- @usage local ws = token(l.WHITESPACE, l.space^1) +-- @usage local annotation = token('annotation', '@' * l.word) +-- @name token +function M.token(name, patt) + return lpeg_Cc(name) * patt * lpeg_Cp() +end + +--- +-- Creates and returns a pattern that matches a range of text bounded by +-- *chars* characters. +-- This is a convenience function for matching more complicated delimited ranges +-- like strings with escape characters and balanced parentheses. *single_line* +-- indicates whether or not the range must be on a single line, *no_escape* +-- indicates whether or not to ignore '\' as an escape character, and *balanced* +-- indicates whether or not to handle balanced ranges like parentheses and +-- requires *chars* to be composed of two characters. +-- @param chars The character(s) that bound the matched range. +-- @param single_line Optional flag indicating whether or not the range must be +-- on a single line. +-- @param no_escape Optional flag indicating whether or not the range end +-- character may be escaped by a '\\' character. +-- @param balanced Optional flag indicating whether or not to match a balanced +-- range, like the "%b" Lua pattern. This flag only applies if *chars* +-- consists of two different characters (e.g. "()"). +-- @return pattern +-- @usage local dq_str_escapes = l.delimited_range('"') +-- @usage local dq_str_noescapes = l.delimited_range('"', false, true) +-- @usage local unbalanced_parens = l.delimited_range('()') +-- @usage local balanced_parens = l.delimited_range('()', false, false, true) +-- @see nested_pair +-- @name delimited_range +function M.delimited_range(chars, single_line, no_escape, balanced) + local s = chars:sub(1, 1) + local e = #chars == 2 and chars:sub(2, 2) or s + local range + local b = balanced and s or '' + local n = single_line and '\n' or '' + if no_escape then + local invalid = lpeg_S(e..n..b) + range = M.any - invalid + else + local invalid = lpeg_S(e..n..b) + '\\' + range = M.any - invalid + '\\' * M.any + end + if balanced and s ~= e then + return lpeg_P{s * (range + lpeg_V(1))^0 * e} + else + return s * range^0 * lpeg_P(e)^-1 + end +end + +--- +-- Creates and returns a pattern that matches pattern *patt* only at the +-- beginning of a line. +-- @param patt The LPeg pattern to match on the beginning of a line. +-- @return pattern +-- @usage local preproc = token(l.PREPROCESSOR, l.starts_line('#') * +-- l.nonnewline^0) +-- @name starts_line +function M.starts_line(patt) + return lpeg_Cmt(lpeg_C(patt), function(input, index, match, ...) + local pos = index - #match + if pos == 1 then return index, ... end + local char = input:sub(pos - 1, pos - 1) + if char == '\n' or char == '\r' or char == '\f' then return index, ... end + end) +end + +--- +-- Creates and returns a pattern that verifies that string set *s* contains the +-- first non-whitespace character behind the current match position. +-- @param s String character set like one passed to `lpeg.S()`. +-- @return pattern +-- @usage local regex = l.last_char_includes('+-*!%^&|=,([{') * +-- l.delimited_range('/') +-- @name last_char_includes +function M.last_char_includes(s) + s = '['..s:gsub('[-%%%[]', '%%%1')..']' + return lpeg_P(function(input, index) + if index == 1 then return index end + local i = index + while input:sub(i - 1, i - 1):match('[ \t\r\n\f]') do i = i - 1 end + if input:sub(i - 1, i - 1):match(s) then return index end + end) +end + +--- +-- Returns a pattern that matches a balanced range of text that starts with +-- string *start_chars* and ends with string *end_chars*. +-- With single-character delimiters, this function is identical to +-- `delimited_range(start_chars..end_chars, false, true, true)`. +-- @param start_chars The string starting a nested sequence. +-- @param end_chars The string ending a nested sequence. +-- @return pattern +-- @usage local nested_comment = l.nested_pair('/*', '*/') +-- @see delimited_range +-- @name nested_pair +function M.nested_pair(start_chars, end_chars) + local s, e = start_chars, lpeg_P(end_chars)^-1 + return lpeg_P{s * (M.any - s - end_chars + lpeg_V(1))^0 * e} +end + +--- +-- Creates and returns a pattern that matches any single word in list *words*. +-- Words consist of alphanumeric and underscore characters, as well as the +-- characters in string set *word_chars*. *case_insensitive* indicates whether +-- or not to ignore case when matching words. +-- This is a convenience function for simplifying a set of ordered choice word +-- patterns. +-- @param words A table of words. +-- @param word_chars Optional string of additional characters considered to be +-- part of a word. By default, word characters are alphanumerics and +-- underscores ("%w_" in Lua). This parameter may be `nil` or the empty string +-- to indicate no additional word characters. +-- @param case_insensitive Optional boolean flag indicating whether or not the +-- word match is case-insensitive. The default is `false`. +-- @return pattern +-- @usage local keyword = token(l.KEYWORD, word_match{'foo', 'bar', 'baz'}) +-- @usage local keyword = token(l.KEYWORD, word_match({'foo-bar', 'foo-baz', +-- 'bar-foo', 'bar-baz', 'baz-foo', 'baz-bar'}, '-', true)) +-- @name word_match +function M.word_match(words, word_chars, case_insensitive) + local word_list = {} + for _, word in ipairs(words) do + word_list[case_insensitive and word:lower() or word] = true + end + local chars = M.alnum + '_' + if word_chars then chars = chars + lpeg_S(word_chars) end + return lpeg_Cmt(chars^1, function(input, index, word) + if case_insensitive then word = word:lower() end + return word_list[word] and index or nil + end) +end + +--- +-- Embeds child lexer *child* in parent lexer *parent* using patterns +-- *start_rule* and *end_rule*, which signal the beginning and end of the +-- embedded lexer, respectively. +-- @param parent The parent lexer. +-- @param child The child lexer. +-- @param start_rule The pattern that signals the beginning of the embedded +-- lexer. +-- @param end_rule The pattern that signals the end of the embedded lexer. +-- @usage l.embed_lexer(M, css, css_start_rule, css_end_rule) +-- @usage l.embed_lexer(html, M, php_start_rule, php_end_rule) +-- @usage l.embed_lexer(html, ruby, ruby_start_rule, ruby_end_rule) +-- @name embed_lexer +function M.embed_lexer(parent, child, start_rule, end_rule) + -- Add child rules. + if not child._EMBEDDEDRULES then child._EMBEDDEDRULES = {} end + if not child._RULES then -- creating a child lexer to be embedded + if not child._rules then error('Cannot embed language with no rules') end + for _, r in ipairs(child._rules) do add_rule(child, r[1], r[2]) end + end + child._EMBEDDEDRULES[parent._NAME] = { + ['start_rule'] = start_rule, + token_rule = join_tokens(child), + ['end_rule'] = end_rule + } + if not parent._CHILDREN then parent._CHILDREN = {} end + local children = parent._CHILDREN + children[#children + 1] = child + -- Add child styles. + if not parent._tokenstyles then parent._tokenstyles = {} end + local tokenstyles = parent._tokenstyles + tokenstyles[child._NAME..'_whitespace'] = M.STYLE_WHITESPACE + for token, style in pairs(child._tokenstyles or {}) do + tokenstyles[token] = style + end + child._lexer = parent -- use parent's tokens if child is embedding itself + parent_lexer = parent -- use parent's tokens if the calling lexer is a proxy +end + +-- Determines if the previous line is a comment. +-- This is used for determining if the current comment line is a fold point. +-- @param prefix The prefix string defining a comment. +-- @param text The text passed to a fold function. +-- @param pos The pos passed to a fold function. +-- @param line The line passed to a fold function. +-- @param s The s passed to a fold function. +local function prev_line_is_comment(prefix, text, pos, line, s) + local start = line:find('%S') + if start < s and not line:find(prefix, start, true) then return false end + local p = pos - 1 + if text:sub(p, p) == '\n' then + p = p - 1 + if text:sub(p, p) == '\r' then p = p - 1 end + if text:sub(p, p) ~= '\n' then + while p > 1 and text:sub(p - 1, p - 1) ~= '\n' do p = p - 1 end + while text:sub(p, p):find('^[\t ]$') do p = p + 1 end + return text:sub(p, p + #prefix - 1) == prefix + end + end + return false +end + +-- Determines if the next line is a comment. +-- This is used for determining if the current comment line is a fold point. +-- @param prefix The prefix string defining a comment. +-- @param text The text passed to a fold function. +-- @param pos The pos passed to a fold function. +-- @param line The line passed to a fold function. +-- @param s The s passed to a fold function. +local function next_line_is_comment(prefix, text, pos, line, s) + local p = text:find('\n', pos + s) + if p then + p = p + 1 + while text:sub(p, p):find('^[\t ]$') do p = p + 1 end + return text:sub(p, p + #prefix - 1) == prefix + end + return false +end + +--- +-- Returns a fold function (to be used within the lexer's `_foldsymbols` table) +-- that folds consecutive line comments that start with string *prefix*. +-- @param prefix The prefix string defining a line comment. +-- @usage [l.COMMENT] = {['--'] = l.fold_line_comments('--')} +-- @usage [l.COMMENT] = {['//'] = l.fold_line_comments('//')} +-- @name fold_line_comments +function M.fold_line_comments(prefix) + local property_int = M.property_int + return function(text, pos, line, s) + if property_int['fold.line.comments'] == 0 then return 0 end + if s > 1 and line:match('^%s*()') < s then return 0 end + local prev_line_comment = prev_line_is_comment(prefix, text, pos, line, s) + local next_line_comment = next_line_is_comment(prefix, text, pos, line, s) + if not prev_line_comment and next_line_comment then return 1 end + if prev_line_comment and not next_line_comment then return -1 end + return 0 + end +end + +M.property_expanded = setmetatable({}, { + -- Returns the string property value associated with string property *key*, + -- replacing any "$()" and "%()" expressions with the values of their keys. + __index = function(t, key) + return M.property[key]:gsub('[$%%]%b()', function(key) + return t[key:sub(3, -2)] + end) + end, + __newindex = function() error('read-only property') end +}) + +--[[ The functions and fields below were defined in C. + +--- +-- Individual fields for a lexer instance. +-- @field _NAME The string name of the lexer. +-- @field _rules An ordered list of rules for a lexer grammar. +-- Each rule is a table containing an arbitrary rule name and the LPeg pattern +-- associated with the rule. The order of rules is important as rules are +-- matched sequentially. +-- Child lexers should not use this table to access and/or modify their +-- parent's rules and vice-versa. Use the `_RULES` table instead. +-- @field _tokenstyles A map of non-predefined token names to styles. +-- Remember to use token names, not rule names. It is recommended to use +-- predefined styles or color-agnostic styles derived from predefined styles +-- to ensure compatibility with user color themes. +-- @field _foldsymbols A table of recognized fold points for the lexer. +-- Keys are token names with table values defining fold points. Those table +-- values have string keys of keywords or characters that indicate a fold +-- point whose values are integers. A value of `1` indicates a beginning fold +-- point and a value of `-1` indicates an ending fold point. Values can also +-- be functions that return `1`, `-1`, or `0` (indicating no fold point) for +-- keys which need additional processing. +-- There is also a required `_pattern` key whose value is a table containing +-- Lua pattern strings that match all fold points (the string keys contained +-- in token name table values). When the lexer encounters text that matches +-- one of those patterns, the matched text is looked up in its token's table +-- to determine whether or not it is a fold point. +-- @field _fold If this function exists in the lexer, it is called for folding +-- the document instead of using `_foldsymbols` or indentation. +-- @field _lexer The parent lexer object whose rules should be used. This field +-- is only necessary to disambiguate a proxy lexer that loaded parent and +-- child lexers for embedding and ended up having multiple parents loaded. +-- @field _RULES A map of rule name keys with their associated LPeg pattern +-- values for the lexer. +-- This is constructed from the lexer's `_rules` table and accessible to other +-- lexers for embedded lexer applications like modifying parent or child +-- rules. +-- @field _LEXBYLINE Indicates the lexer can only process one whole line of text +-- (instead of an arbitrary chunk of text) at a time. +-- The default value is `false`. Line lexers cannot look ahead to subsequent +-- lines. +-- @field _FOLDBYINDENTATION Declares the lexer does not define fold points and +-- that fold points should be calculated based on changes in indentation. +-- @class table +-- @name lexer +local lexer +]] + +return M |