From b6a33e1c2e2ff06c59940707f24f55fb4c396cae Mon Sep 17 00:00:00 2001
From: s1yle <1373003655@qq.com>
Date: Fri, 9 Jan 2026 15:56:58 +0800
Subject: [PATCH] fix: proper tab handling in lexer and font metrics

---
 src/free_glyph.c | 10 ++++++++++
 src/lexer.c      | 16 +++++++++++++++-
 src/lexer.h      |  1 +
 src/main.c       |  4 +---
 4 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/free_glyph.c b/src/free_glyph.c
index fe2b55b3..4cd3adda 100644
--- a/src/free_glyph.c
+++ b/src/free_glyph.c
@@ -73,6 +73,16 @@ void free_glyph_atlas_init(Free_Glyph_Atlas *atlas, FT_Face face)
             face->glyph->bitmap.buffer);
         x += face->glyph->bitmap.width;
     }
+
+    // Set tab character metric as 4 times the space metric
+    Glyph_Metric space_metric = atlas->metrics[(size_t)' '];
+    atlas->metrics[(size_t)'\t'].ax = space_metric.ax * 4;
+    atlas->metrics[(size_t)'\t'].ay = space_metric.ay;
+    atlas->metrics[(size_t)'\t'].bw = space_metric.bw;
+    atlas->metrics[(size_t)'\t'].bh = space_metric.bh;
+    atlas->metrics[(size_t)'\t'].bl = space_metric.bl;
+    atlas->metrics[(size_t)'\t'].bt = space_metric.bt;
+    atlas->metrics[(size_t)'\t'].tx = space_metric.tx;
 }
 
 float free_glyph_atlas_cursor_pos(const Free_Glyph_Atlas *atlas, const char *text, size_t text_size, Vec2f pos, size_t col)
diff --git a/src/lexer.c b/src/lexer.c
index cfd9022c..988c412e 100644
--- a/src/lexer.c
+++ b/src/lexer.c
@@ -102,6 +102,11 @@ void lexer_chop_char(Lexer *l, size_t len)
             l->line += 1;
             l->bol = l->cursor;
             l->x = 0;
+        } else if(x == '\t') {
+            if(l->atlas) {
+                Glyph_Metric space_metric = l->atlas->metrics[(size_t)' '];
+                l->x += space_metric.ax * 4;
+            }
         } else {
             if (l->atlas) {
                 size_t glyph_index = x;
@@ -118,7 +123,9 @@ void lexer_chop_char(Lexer *l, size_t len)
 
 void lexer_trim_left(Lexer *l)
 {
-    while (l->cursor < l->content_len && isspace(l->content[l->cursor])) {
+    while (l->cursor < l->content_len && isspace(l->content[l->cursor])
+     && l->content[l->cursor] != '\t'
+    ) {
         lexer_chop_char(l, 1);
     }
 }
@@ -146,6 +153,13 @@ Token lexer_next(Lexer *l)
 
     if (l->cursor >= l->content_len) return token;
 
+    if (l->content[l->cursor] == '\t') {
+         token.kind = TOKEN_TAB;
+         token.text_len = 1;
+         lexer_chop_char(l, 1);
+         return token;
+    }
+
     if (l->content[l->cursor] == '"') {
         // TODO: TOKEN_STRING should also handle escape sequences
         token.kind = TOKEN_STRING;
diff --git a/src/lexer.h b/src/lexer.h
index 6ee721ed..885c813c 100644
--- a/src/lexer.h
+++ b/src/lexer.h
@@ -8,6 +8,7 @@
 typedef enum {
     TOKEN_END = 0,
     TOKEN_INVALID,
+    TOKEN_TAB,
     TOKEN_PREPROC,
     TOKEN_SYMBOL,
     TOKEN_OPEN_PAREN,
diff --git a/src/main.c b/src/main.c
index eac9ac5f..35120c14 100644
--- a/src/main.c
+++ b/src/main.c
@@ -328,9 +328,7 @@ int main(int argc, char **argv)
                         // - tabs/spaces
                         // - tab width
                         // - etc.
-                        for (size_t i = 0; i < 4; ++i) {
-                            editor_insert_char(&editor, ' ');
-                        }
+                        editor_insert_char(&editor, '\t');
                     }
                     break;