From d94bb93f10365a39d90cc0d4d4b151fc797767df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc=20Andr=C3=A9=20Tanner?= <mat@brain-dump.org>
Date: Sat, 30 Jan 2016 20:11:52 +0100
Subject: Implement blackhole register "_

---
 main.c     |  2 ++
 register.c | 43 +++++++++++++++++++++++++++++++++----------
 register.h |  4 ++++
 vis.c      |  1 +
 vis.h      |  1 +
 5 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/main.c b/main.c
index 03a1362..487ce3c 100644
--- a/main.c
+++ b/main.c
@@ -1306,6 +1306,8 @@ static const char *key2register(Vis *vis, const char *keys, enum VisRegister *re
 		return NULL;
 	if (keys[0] >= 'a' && keys[0] <= 'z')
 		*reg = keys[0] - 'a';
+	else if (keys[0] == '_')
+		*reg = VIS_REG_BLACKHOLE;
 	return keys+1;
 }
 
diff --git a/register.c b/register.c
index 30ad19c..30e4c58 100644
--- a/register.c
+++ b/register.c
@@ -11,22 +11,45 @@ void register_release(Register *reg) {
 }
 
 const char *register_get(Register *reg, size_t *len) {
-	*len = reg->buf.len;
-	return reg->buf.data;
+	switch (reg->type) {
+	case REGISTER_NORMAL:
+		*len = reg->buf.len;
+		return reg->buf.data;
+	case REGISTER_BLACKHOLE:
+	default:
+		*len = 0;
+		return NULL;
+	}
 }
 
 bool register_put(Register *reg, Text *txt, Filerange *range) {
-	size_t len = text_range_size(range);
-	if (!buffer_grow(&reg->buf, len))
+	switch (reg->type) {
+	case REGISTER_NORMAL:
+	{
+		size_t len = text_range_size(range);
+		if (!buffer_grow(&reg->buf, len))
+			return false;
+		reg->buf.len = text_bytes_get(txt, range->start, len, reg->buf.data);
+		return true;
+	}
+	case REGISTER_BLACKHOLE:
+		return true;
+	default:
 		return false;
-	reg->buf.len = text_bytes_get(txt, range->start, len, reg->buf.data);
-	return true;
+	}
 }
 
 bool register_append(Register *reg, Text *txt, Filerange *range) {
-	size_t len = text_range_size(range);
-	if (!buffer_grow(&reg->buf, reg->buf.len + len))
+	switch (reg->type) {
+	case REGISTER_NORMAL:
+	{
+		size_t len = text_range_size(range);
+		if (!buffer_grow(&reg->buf, reg->buf.len + len))
+			return false;
+		reg->buf.len += text_bytes_get(txt, range->start, len, reg->buf.data + reg->buf.len);
+		return true;
+	}
+	default:
 		return false;
-	reg->buf.len += text_bytes_get(txt, range->start, len, reg->buf.data + reg->buf.len);
-	return true;
+	}
 }
diff --git a/register.h b/register.h
index 22edd22..1b14688 100644
--- a/register.h
+++ b/register.h
@@ -9,6 +9,10 @@
 typedef struct {
 	Buffer buf;
 	bool linewise; /* place register content on a new line when inserting? */
+	enum {
+		REGISTER_NORMAL,
+		REGISTER_BLACKHOLE,
+	} type;
 } Register;
 
 void register_release(Register *reg);
diff --git a/vis.c b/vis.c
index c7089ca..3edc766 100644
--- a/vis.c
+++ b/vis.c
@@ -315,6 +315,7 @@ Vis *vis_new(Ui *ui, VisEvent *event) {
 	vis->ui->init(vis->ui, vis);
 	vis->tabwidth = 8;
 	vis->expandtab = false;
+	vis->registers[VIS_REG_BLACKHOLE].type = REGISTER_BLACKHOLE;
 	action_reset(&vis->action);
 	if (!(vis->search_pattern = text_regex_new()))
 		goto err;
diff --git a/vis.h b/vis.h
index fe30fa4..8de1f51 100644
--- a/vis.h
+++ b/vis.h
@@ -348,6 +348,7 @@ enum VisRegister {
 	VIS_REG_u, VIS_REG_v, VIS_REG_w, VIS_REG_x, VIS_REG_y,
 	VIS_REG_z,
 	VIS_REG_DEFAULT, /* used when no other register is specified */
+	VIS_REG_BLACKHOLE, /* /dev/null register */
 	VIS_REG_PROMPT,  /* internal register which shadows DEFAULT in PROMPT mode */
 	VIS_REG_INVALID, /* has to be the last enum member */
 };
-- 
cgit v1.2.3