Add syntax highlighting

kilo.c

@@ -38,14 +38,33 @@ enum editorKey {
   PAGE_DOWN
 };
 
+enum editorHighlight {
+  HL_NORMAL = 0,
+  HL_COMMENT,
+  HL_STRING,
+  HL_NUMBER,
+  HL_MATCH
+};
+
+#define HL_HIGHLIGHT_NUMBERS (1<<0)
+#define HL_HIGHLIGHT_STRINGS (1<<1)
+
 
 /*** data ***/
 
+struct editorSyntax {
+  char *filetype;
+  char **filematch;
+  char *singleline_comment_start;
+  int flags;
+};
+
 typedef struct erow {
   int size;
   int rsize;
   char *chars;
   char *render;
+  unsigned char *hl;
 } erow;
 
 struct editorConfig {
@@ -61,11 +80,27 @@ struct editorConfig {
   char *filename;
   char statusmsg[80];
   time_t statusmsg_time;
+  struct editorSyntax *syntax;
   struct termios orig_termios;
 };
 
 struct editorConfig E;
 
+/*** filetypes ***/
+
+char *C_HL_extensions[] = { ".c", ".h", ".cpp", NULL };
+
+struct editorSyntax HLDB[] = {
+  {
+    "c",
+    C_HL_extensions,
+    "//",
+    HL_HIGHLIGHT_NUMBERS | HL_HIGHLIGHT_STRINGS
+  },
+};
+
+#define HLDB_ENTRIES (sizeof(HLDB) / sizeof(HLDB[0]))
+
 /*** prototypes ***/
 
 void editorSetStatusMessage(const char *fmt, ...);
@@ -189,6 +224,112 @@ int getWindowSize(int *rows, int *cols) {
   }
 }
 
+/*** syntax highlighting ***/
+
+int is_separator(int c) {
+  return isspace(c) || c == '\0' || strchr(",.()+-/*=~%<>[];", c) != NULL;
+}
+
+void editorUpdateSyntax(erow *row) {
+  row->hl = realloc(row->hl, row->rsize);
+  memset(row->hl, HL_NORMAL, row->rsize);
+
+  if (E.syntax == NULL) return;
+
+  char *scs = E.syntax->singleline_comment_start;
+  int scs_len = scs ? strlen(scs) : 0;
+
+  int prev_sep = 1;
+  int in_string = 0;
+
+  int i = 0;
+  while (i < row->rsize) {
+    char c = row->render[i];
+    unsigned char prev_hl = (i > 0) ? row->hl[i -1] : HL_NORMAL;
+
+    // Comments
+    if (scs_len && !in_string) {
+      if (!strncmp(&row->render[i], scs, scs_len)) {
+        memset(&row->hl[i], HL_COMMENT, row->rsize - i);
+        break;
+      }
+    }
+
+    // Strings
+    if (E.syntax->flags & HL_HIGHLIGHT_NUMBERS) {
+      if (in_string) {
+        row->hl[i] = HL_STRING;
+        if (c == '\\' && i + 1 < row->rsize) {
+          row->hl[i + 1] = HL_STRING;
+          i += 2;
+          continue;
+        }
+        if (c == in_string) in_string = 0;
+        i++;
+        prev_sep = 1;
+        continue;
+      } else {
+        if (c == '"' || c == '\'') {
+          in_string = c;
+          row->hl[i] = HL_STRING;
+          i++;
+          continue;
+        }
+      }
+    }
+
+    // Numbers
+    if (E.syntax->flags & HL_HIGHLIGHT_NUMBERS) {
+      if ((isdigit(c) && (prev_sep || prev_hl == HL_NUMBER)) ||
+          (c == '.' && prev_hl == HL_NUMBER)) {
+        row->hl[i] = HL_NUMBER;
+        i++;
+        prev_sep = 0;
+        continue;
+      }
+    }
+
+    prev_sep = is_separator(c);
+    i++;
+  }
+}
+
+int editorSyntaxToColor(int hl) {
+  switch (hl) {
+    case HL_COMMENT: return 36;
+    case HL_STRING: return 35;
+    case HL_NUMBER: return 31;
+    case HL_MATCH: return 34;
+    default: return 37;
+  }
+}
+
+void editorSelectSyntaxHighlight() {
+  E.syntax = NULL;
+  if (E.filename == NULL) return;
+
+  char *ext = strrchr(E.filename, '.');
+
+  for (unsigned int j=0; j<HLDB_ENTRIES; j++) {
+    struct editorSyntax *s = &HLDB[j];
+    unsigned int i = 0;
+    while (s->filematch[i]) {
+      int is_ext = (s->filematch[i][0] == '.');
+      if ((is_ext && ext && !strcmp(ext, s->filematch[i])) ||
+          (!is_ext && strstr(E.filename, s->filematch[i]))) {
+        E.syntax = s;
+
+        int filerow;
+        for (filerow=0; filerow<E.numrows; filerow++) {
+          editorUpdateSyntax(&E.row[filerow]);
+        }
+        return;
+      }
+      i++;
+    }
+  }
+}
+
 /*** row operations ***/
 
 int editorRowCxToRx(erow *row, int cx) {
@@ -237,6 +378,8 @@ void editorUpdateRow(erow *row) {
   }
   row->render[idx] = '\0';
   row->rsize = idx;
+
+  editorUpdateSyntax(row);
 }
 
 void editorInsertRow(int at, char *s, size_t len) {
@@ -252,6 +395,7 @@ void editorInsertRow(int at, char *s, size_t len) {
 
   E.row[at].rsize = 0;
   E.row[at].render = NULL;
+  E.row[at].hl = NULL;
   editorUpdateRow(&E.row[at]);
 
   E.numrows++;
@@ -261,6 +405,7 @@ void editorInsertRow(int at, char *s, size_t len) {
 void editorFreeRow(erow *row) {
   free(row->render);
   free(row->chars);
+  free(row->hl);
 }
 
 void editorDelRow(int at) {
@@ -367,6 +512,8 @@ void editorOpen(char *filename) {
   free(E.filename);
   E.filename = strdup(filename);
 
+  editorSelectSyntaxHighlight();
+
   FILE *fp = fopen(filename, "r");
   if (!fp) die("fopen");
 
@@ -406,6 +553,7 @@ void editorSave() {
         editorSetStatusMessage("%d bytes written to disk", len);
         return;
       }
+      editorSelectSyntaxHighlight();
     }
     close(fd);
   }
@@ -420,6 +568,15 @@ void editorFindCallback(char *query, int key) {
   static int last_match = -1;
   static int direction = 1;
 
+  static int saved_hl_line;
+  static char *saved_hl = NULL;
+
+  if (saved_hl) {
+    memcpy(E.row[saved_hl_line].hl, saved_hl, E.row[saved_hl_line].rsize);
+    free(saved_hl);
+    saved_hl = NULL;
+  }
+  
   if (key == '\r' || key == '\xb') {
     last_match = -1;
     direction = 1;
@@ -449,6 +606,11 @@ void editorFindCallback(char *query, int key) {
       E.cy = current;
       E.cx = editorRowRxToCx(row, match - row->render); // Substract pointers here
       E.rowoff = E.numrows;
+
+      saved_hl_line = current;
+      saved_hl = malloc(row->rsize);
+      memcpy(saved_hl, row->hl, row->rsize);
+      memset(&row->hl[match - row->render], HL_MATCH, strlen(query));
       break;
     }
   }
@@ -538,16 +700,28 @@ void editorDrawRows(struct abuf *ab) {
       if (len < 0) len = 0;
       if (len > E.screencols) len = E.screencols;
       char *c = &E.row[filerow].render[E.coloff];
+      unsigned char *hl = &E.row[filerow].hl[E.coloff];
+      int current_color = -1;
       int j;
       for (j=0; j<len; j++) {
-        if (isdigit(c[j])) {
+        if (hl[j] == HL_NORMAL) {
-          abAppend(ab, "\x1b[31m", 5);
+          if (current_color != -1) {
+            abAppend(ab, "\x1b[39m", 5);
+            current_color = -1;
+          }
           abAppend(ab, &c[j], 1);
-          abAppend(ab, "\x1b[39m", 5);
         } else {
+          int color = editorSyntaxToColor(hl[j]);
+          if (color != current_color) {
+            current_color = color;
+            char buf[16];
+            int clen = snprintf(buf, sizeof(buf), "\x1b[%dm", color);
+            abAppend(ab, buf, clen);
+          }
           abAppend(ab, &c[j], 1);
         }
       }
+      abAppend(ab, "\x1b[39m", 5);
     }
 
     abAppend(ab, "\x1b[K", 3); // Erase one line
@@ -561,8 +735,8 @@ void editorDrawStatusBar(struct abuf *ab) {
   int len = snprintf(status, sizeof(status), "%.20s - %d lines %s",
       E.filename ? E.filename : "[No Name]", E.numrows,
       E.dirty ? "(modified)" : "");
-  int rlen = snprintf(rstatus, sizeof(rstatus), "%d/%d",
+  int rlen = snprintf(rstatus, sizeof(rstatus), "%s | %d/%d",
-      E.cy + 1, E.numrows);
+      E.syntax ? E.syntax->filetype : "no ft", E.cy + 1, E.numrows);
   if (len > E.screencols) len = E.screencols;
   abAppend(ab, status, len);
   while (len < E.screencols) {
@@ -791,6 +965,7 @@ void initEditor() {
   E.filename = NULL;
   E.statusmsg[0] = '\0';
   E.statusmsg_time = 0;
+  E.syntax = NULL;
 
   if (getWindowSize(&E.screenrows, &E.screencols) == -1)
       die("getWindowSize");