Add line numbering to editor.

doc/user-guide

@@ -320,6 +320,7 @@ simple to use. It currently supports these keyboard commands:
 * `Ctrl-V` - Paste
 * `Ctrl-X` - Cut
 * `ESC language <c or c++>` - enable syntax highlighting
+* `ESC line-numbering <on or off>` - enable line numbering
 * `ESC margin <column>` - add right margin at column
 * `ESC popen <command>` - open command output
 * `ESC tabsize <desired-tab-size>` - change tab size

editor/display.c++

@@ -26,6 +26,7 @@
 
 #include <stddef.h>
 #include <stdlib.h>
+#include <string.h>
 #include <wchar.h>
 
 #include "display.h++"
@@ -138,9 +139,15 @@ void render_editor(struct editor* editor, struct terminal_state* state)
 			state->data[header_start_len+i].character = wcs_file_name[i];
 	free(wcs_file_name);
 
+	size_t line_number_width = 1;
+	for ( size_t tmp = editor->lines_used; 10 <= tmp; tmp /= 10 )
+		line_number_width++;
+	if ( !editor->line_numbering )
+		line_number_width = 0;
+
 	// Calculate the dimensions of the viewport.
 	size_t viewport_top = 1;
-	size_t viewport_left = 0;
+	size_t viewport_left = line_number_width;
 
 	editor->viewport_width = (size_t) state->width;
 	if ( editor->viewport_width < viewport_left )
@@ -202,6 +209,17 @@ void render_editor(struct editor* editor, struct terminal_state* state)
 			chars = NULL, chars_length = 0;
 		else
 			chars += page_x_offset, chars_length -= page_x_offset;
+		for ( size_t x = 0; x < line_number_width; x++ )
+			raw_data_line[x] = make_terminal_datum(L' ', 0x70);
+		if ( editor->line_numbering && line_index < editor->lines_used )
+		{
+			char line_number[sizeof(size_t) * 3];
+			snprintf(line_number, sizeof(line_number), "%zu", line_index + 1);
+			size_t length = strlen(line_number);
+			size_t offset = line_number_width - length;
+			for ( size_t i = 0; i < length; i++ )
+				raw_data_line[offset + i].character = btowc(line_number[i]);
+		}
 		for ( size_t x = 0; x < editor->viewport_width; x++ )
 		{
 			size_t column_index = page_x_offset + x;

editor/editor.h++

@@ -83,6 +83,7 @@ struct editor
 	bool dirty;
 	bool modal_error;
 	bool highlight_source;
+	bool line_numbering;
 };
 
 __attribute__((unused))

editor/modal.c++

@@ -37,6 +37,16 @@
 #include "modal.h++"
 #include "multibyte.h++"
 
+bool is_truth_string(const char* truth)
+{
+	return !strcmp(truth, "on") || !strcmp(truth, "off");
+}
+
+bool is_truth_true(const char* truth)
+{
+	return strcmp(truth, "off") != 0;
+}
+
 void editor_modal_left(struct editor* editor)
 {
 	if ( editor->modal_cursor )
@@ -210,6 +220,17 @@ void editor_modal_language(struct editor* editor, const char* language)
 	editor_type_edit(editor);
 }
 
+void editor_modal_line_numbering(struct editor* editor, const char* truth)
+{
+	if ( !is_truth_string(truth) )
+	{
+		editor->modal_error = true;
+		return;
+	}
+	editor->line_numbering = is_truth_true(truth);
+	editor_type_edit(editor);
+}
+
 bool is_modal_command(const char* cmd, const char* candidate, const char** rest)
 {
 	size_t candidate_len = strlen(candidate);
@@ -249,6 +270,8 @@ void editor_modal_command(struct editor* editor, const char* cmd)
 		editor_modal_tabsize(editor, cmd);
 	else if ( is_modal_command(cmd, "language", &cmd) )
 		editor_modal_language(editor, cmd);
+	else if ( is_modal_command(cmd, "line-numbering", &cmd) )
+		editor_modal_line_numbering(editor, cmd);
 	else
 		editor->modal_error = true;
 }

editor/modal.h++

@@ -25,6 +25,9 @@
 
 struct editor;
 
+bool is_truth_string(const char* truth);
+bool is_truth_true(const char* truth);
+
 void editor_modal_left(struct editor* editor);
 void editor_modal_right(struct editor* editor);
 void editor_modal_home(struct editor* editor);
@@ -40,6 +43,7 @@ void editor_modal_margin(struct editor* editor, const char* marginstr);
 void editor_modal_popen(struct editor* editor, const char* cmd);
 void editor_modal_tabsize(struct editor* editor, const char* tabsizestr);
 void editor_modal_language(struct editor* editor, const char* language);
+void editor_modal_line_numbering(struct editor* editor, const char* truth);
 
 bool is_modal_command(const char* cmd, const char* candidate, const char** rest);
 void editor_modal_command(struct editor* editor, const char* cmd);