feat(lexer): match check boxes

include/mrk/lexer.h

@@ -34,6 +34,8 @@ typedef enum mrk_token_type {
   mrk_token_type_backslash,
   mrk_token_type_dotted_number,
   mrk_token_type_word,
+  mrk_token_type_checked_box,
+  mrk_token_type_unchecked_box,
 } mrk_token_type;
 
 typedef struct mrk_token {

src/_include/mrk/lexer_internal.h

@@ -33,10 +33,11 @@ char mrk_lexer_peek(mrk_lexer *lexer);
 char mrk_lexer_peek_n(mrk_lexer *lexer, size_t n);
 
 /**
- * Returns true if the nul-terminated string s is equal to the next characters
- * in the token stream.
+ * Returns true if the nul-terminated string s matches the next characters that
+ * would be consumed. This is a convenience method instead of having to call
+ * multiple peek calls.
  */
-bool mrk_lexer_match(mrk_lexer *lexer, const char *s);
+bool mrk_lexer_peek_str(mrk_lexer *lexer, const char *s);
 
 /**
  * Advance the current position by one character, adding the new character to

src/lexer/lexer.c

@@ -84,6 +84,24 @@ void mrk_lexer_advance_word(mrk_lexer *lexer) {
   }
 }
 
+bool mrk_lexer_peek_str(mrk_lexer *lexer, const char *s) {
+  bool match = true;
+
+  size_t i = 0;
+  while (*s != '\0') {
+    // Check whether the lexer would be done before matching the entire string
+    bool done_in_n =
+        (lexer->buf.len > 0 && lexer->pos.buf_index + i == lexer->buf.len) ||
+        (lexer->buf.s[lexer->pos.buf_index + i] == '\0');
+    match = !done_in_n && (lexer->buf.s[lexer->pos.buf_index + i] == *s);
+
+    i++;
+    s++;
+  }
+
+  return match;
+}
+
 char mrk_lexer_peek_n(mrk_lexer *lexer, size_t n) {
   // Check whether the lexer would be done in n steps
   bool done_in_n = false;
@@ -97,14 +115,6 @@ char mrk_lexer_peek_n(mrk_lexer *lexer, size_t n) {
   return done_in_n ? '\0' : lexer->buf.s[lexer->pos.buf_index + n];
 }
 
-/* bool mrk_lexer_match(mrk_lexer *lexer, const char *s) { */
-/*   size_t s_len = strlen(s); */
-/*   if (mrk_lexer_done(lexer) && s[0] != '\0') { */
-/*     return false; */
-/*   } */
-
-/* } */
-
 void mrk_lexer_reset(mrk_lexer *lexer) {
   lexer->token.start = lexer->pos.buf_index;
   lexer->token.end = lexer->pos.buf_index;
@@ -168,7 +178,17 @@ mrk_lexer_err mrk_lexer_next(mrk_token *out, mrk_lexer *lexer) {
       mrk_lexer_emit(out, lexer, mrk_token_type_bang);
       break;
     case '[':
+      // Checkboxes for lists are lexed separately to simplify the parser later
+      // on
+      if (mrk_lexer_peek_str(lexer, " ]")) {
+        mrk_lexer_advance_n(lexer, 2);
+        mrk_lexer_emit(out, lexer, mrk_token_type_unchecked_box);
+      } else if (mrk_lexer_peek_str(lexer, "x]")) {
+        mrk_lexer_advance_n(lexer, 2);
+        mrk_lexer_emit(out, lexer, mrk_token_type_checked_box);
+      } else {
         mrk_lexer_emit(out, lexer, mrk_token_type_left_bracket);
+      }
       break;
     case ']':
       mrk_lexer_emit(out, lexer, mrk_token_type_right_bracket);
@@ -198,7 +218,7 @@ mrk_lexer_err mrk_lexer_next(mrk_token *out, mrk_lexer *lexer) {
       break;
     case ' ': {
       // Either a double space or a line break
-      if (mrk_lexer_peek(lexer) == ' ' && mrk_lexer_peek_n(lexer, 1) == '\n') {
+      if (mrk_lexer_peek_str(lexer, " \n")) {
         mrk_lexer_advance_n(lexer, 2);
 
         mrk_lexer_emit(out, lexer, mrk_token_type_line_break);