Move all lua related files to lua/ subfolder

Also remove the lexers sub directory from the Lua search path.
As a result we attempt to open fewer files during startup:

 $ strace -e open -o log ./vis +q config.h && wc -l log

In order to avoid having to modifiy all lexers which `require('lexer')`
we instead place a symlink in the top level directory.

 $ ./configure --disable-lua
 $ rm -rf lua

Should result in a source tree with most lua specifc functionality
removed.

1 files changed, 108 insertions, 0 deletions

diff --git a/lua/lexers/makefile.lua b/lua/lexers/makefile.lua
new file mode 100644
index 0000000..45eb310
--- /dev/null
+++ b/lua/lexers/makefile.lua
@@ -0,0 +1,108 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Makefile 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 = 'makefile'}
+
+-- Whitespace.
+local ws = token(l.WHITESPACE, l.space^1)
+
+-- Comments.
+local comment = token(l.COMMENT, '#' * l.nonnewline^0)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, P('!')^-1 * l.word_match({
+  -- GNU Make conditionals.
+  'ifeq', 'ifneq', 'ifdef', 'ifndef', 'else', 'endif',
+  -- Other conditionals.
+  'if', 'elseif', 'elseifdef', 'elseifndef',
+  -- Directives and other keywords.
+  'define', 'endef', 'export', 'include', 'override', 'private', 'undefine',
+  'unexport', 'vpath'
+}, nil, true))
+
+-- Functions.
+local func = token(l.FUNCTION, l.word_match({
+  -- Functions for String Substitution and Analysis.
+  'subst', 'patsubst', 'strip', 'findstring', 'filter', 'filter-out', 'sort',
+  'word', 'wordlist', 'words', 'firstword', 'lastword',
+  -- Functions for File Names.
+  'dir', 'notdir', 'suffix', 'basename', 'addsuffix', 'addprefix', 'join',
+  'wildcard', 'realpath', 'abspath',
+  -- Functions for Conditionals.
+  'if', 'or', 'and',
+  -- Miscellaneous Functions.
+  'foreach', 'call', 'value', 'eval', 'origin', 'flavor', 'shell',
+  -- Functions That Control Make.
+  'error', 'warning', 'info'
+}), '-')
+
+-- Variables.
+local word_char, assign = l.any - l.space - S(':#=(){}'), S(':+?')^-1 * '='
+local expanded_var = '$' * ('(' * word_char^1 * ')' + '{' * word_char^1 * '}')
+local auto_var = '$' * S('@%<?^+|*')
+local special_var = l.word_match({
+  'MAKEFILE_LIST', '.DEFAULT_GOAL', 'MAKE_RESTARTS', '.RECIPEPREFIX',
+  '.VARIABLES', '.FEATURES', '.INCLUDE_DIRS',
+  'GPATH', 'MAKECMDGOALS', 'MAKESHELL', 'SHELL', 'VPATH'
+}, '.') * #(ws^0 * assign)
+local implicit_var = l.word_match{
+  -- Some common variables.
+  'AR', 'AS', 'CC', 'CXX', 'CPP', 'FC', 'M2C', 'PC', 'CO', 'GET', 'LEX', 'YACC',
+  'LINT', 'MAKEINFO', 'TEX', 'TEXI2DVI', 'WEAVE', 'CWEAVE', 'TANGLE', 'CTANGLE',
+  'RM',
+  -- Some common flag variables.
+  'ARFLAGS', 'ASFLAGS', 'CFLAGS', 'CXXFLAGS', 'COFLAGS', 'CPPFLAGS', 'FFLAGS',
+  'GFLAGS', 'LDFLAGS', 'LFLAGS', 'YFLAGS', 'PFLAGS', 'RFLAGS', 'LINTFLAGS',
+  -- Other.
+  'DESTDIR', 'MAKE', 'MAKEFLAGS', 'MAKEOVERRIDES', 'MFLAGS'
+} * #(ws^0 * assign)
+local computed_var = token(l.OPERATOR, '$' * S('({')) * func
+local variable = token(l.VARIABLE,
+                       expanded_var + auto_var + special_var + implicit_var) +
+                 computed_var
+
+-- Targets.
+local special_target = token(l.CONSTANT, l.word_match({
+  '.PHONY', '.SUFFIXES', '.DEFAULT', '.PRECIOUS', '.INTERMEDIATE', '.SECONDARY',
+  '.SECONDEXPANSION', '.DELETE_ON_ERROR', '.IGNORE', '.LOW_RESOLUTION_TIME',
+  '.SILENT', '.EXPORT_ALL_VARIABLES', '.NOTPARALLEL', '.ONESHELL', '.POSIX'
+}, '.'))
+local normal_target = token('target', (l.any - l.space - S(':#='))^1)
+local target = l.starts_line((special_target + normal_target) * ws^0 *
+                             #(':' * -P('=')))
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, word_char^1)
+
+-- Operators.
+local operator = token(l.OPERATOR, assign + S(':$(){}'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'target', target},
+  {'variable', variable},
+  {'operator', operator},
+  {'identifier', identifier},
+  {'comment', comment},
+}
+
+M._tokenstyles = {
+  target = l.STYLE_LABEL
+}
+
+M._LEXBYLINE = true
+
+-- Embedded Bash.
+local bash = l.load('bash')
+bash._RULES['variable'] = token(l.VARIABLE, '$$' * word_char^1) +
+                          bash._RULES['variable'] + variable
+local bash_start_rule = token(l.WHITESPACE, P('\t')) + token(l.OPERATOR, P(';'))
+local bash_end_rule = token(l.WHITESPACE, P('\n'))
+l.embed_lexer(M, bash, bash_start_rule, bash_end_rule)
+
+return M