feat(lexer): matching more things

src/_include/mrk/lexer_internal.h

@@ -26,6 +26,12 @@ struct mrk_lexer {
  */
 char mrk_lexer_peek(mrk_lexer *lexer);
 
+/**
+ * Return the n'th next character that would be consumed. If `n` is zero, this
+ * function is equivalent to calling peek.
+ */
+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.
@@ -38,6 +44,11 @@ bool mrk_lexer_match(mrk_lexer *lexer, const char *s);
  */
 char mrk_lexer_advance(mrk_lexer *lexer);
 
+/**
+ * Advance until the next element to peek is not equal to c.
+ */
+void mrk_lexer_advance_eq(mrk_lexer *lexer, char c);
+
 /**
  * Advance `n` positions; equivalent to running advance `n` times and returning
  * the last call's result.

src/lexer/lexer.c

@@ -1,3 +1,6 @@
+#include <ctype.h>
+#include <stdio.h>
+
 #include "mrk/lexer.h"
 #include "mrk/lexer_internal.h"
 
@@ -55,11 +58,18 @@ char mrk_lexer_advance(mrk_lexer *lexer) {
 char mrk_lexer_advance_n(mrk_lexer *lexer, size_t n) {
   while (n > 1) {
     mrk_lexer_advance(lexer);
+    n--;
   }
 
   return mrk_lexer_advance(lexer);
 }
 
+void mrk_lexer_advance_eq(mrk_lexer *lexer, char c) {
+  while (mrk_lexer_peek(lexer) == c) {
+    mrk_lexer_advance(lexer);
+  }
+}
+
 char mrk_lexer_peek(mrk_lexer *lexer) {
   if (mrk_lexer_done(lexer)) {
     return '\0';
@@ -68,6 +78,27 @@ char mrk_lexer_peek(mrk_lexer *lexer) {
   return lexer->buf.s[lexer->pos.buf_index];
 }
 
+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;
+
+  for (size_t i = 0; i < n && !done_in_n; i++) {
+    done_in_n =
+        (lexer->buf.len > 0 && lexer->pos.buf_index + i == lexer->buf.len) ||
+        (lexer->buf.s[lexer->pos.buf_index + i] == '\0');
+  }
+
+  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;
@@ -90,14 +121,29 @@ mrk_lexer_err mrk_lexer_next(mrk_token *out, mrk_lexer *lexer) {
   mrk_lexer_reset(lexer);
 
   while (!lexer->token.emitted && !mrk_lexer_done(lexer)) {
-    switch (mrk_lexer_advance(lexer)) {
-    // Match one or more hashtags as a single header definition
+    char c = mrk_lexer_advance(lexer);
+    switch (c) {
+    // All these characters have multiple meanings depending on their location
+    // in the file and how many there are
     case '#':
-      while (mrk_lexer_peek(lexer) == '#') {
-        mrk_lexer_advance(lexer);
-      }
-
-      mrk_lexer_emit(out, lexer, mrk_token_type_header);
+      mrk_lexer_advance_eq(lexer, c);
+      mrk_lexer_emit(out, lexer, mrk_token_type_pounds);
+      break;
+    case '`':
+      mrk_lexer_advance_eq(lexer, c);
+      mrk_lexer_emit(out, lexer, mrk_token_type_backticks);
+      break;
+    case '-':
+      mrk_lexer_advance_eq(lexer, c);
+      mrk_lexer_emit(out, lexer, mrk_token_type_dashes);
+      break;
+    case '_':
+      mrk_lexer_advance_eq(lexer, c);
+      mrk_lexer_emit(out, lexer, mrk_token_type_underscores);
+      break;
+    case '*':
+      mrk_lexer_advance_eq(lexer, c);
+      mrk_lexer_emit(out, lexer, mrk_token_type_stars);
       break;
       // Two consecutive newlines constitute a blank line, otherwise they're
       // ignored as whitespace
@@ -110,29 +156,22 @@ mrk_lexer_err mrk_lexer_next(mrk_token *out, mrk_lexer *lexer) {
       }
       break;
     case ' ': {
+      /* if (mrk_lexer_peek(lexer) == ' ' && mrk_lexer_peek_n(lexer,)) */
       // Either a double space or a line break
-      if (mrk_lexer_peek(lexer) == ' ') {
-        mrk_lexer_advance(lexer);
+      if (mrk_lexer_peek(lexer) == ' ' && mrk_lexer_peek_n(lexer, 1) == '\n') {
+        mrk_lexer_advance_n(lexer, 2);
 
-        if (mrk_lexer_peek(lexer) == '\n') {
-          mrk_lexer_advance(lexer);
-          mrk_lexer_emit(out, lexer, mrk_token_type_line_break);
-        } else {
-          mrk_lexer_emit(out, lexer, mrk_token_type_space_space);
-        }
+        mrk_lexer_emit(out, lexer, mrk_token_type_line_break);
       } else {
-        mrk_lexer_reset(lexer);
+        mrk_lexer_emit(out, lexer, mrk_token_type_space);
       }
     } break;
-      /* case '*': */
-      /*   if (mrk_lexer_peek(lexer) == '*') { */
-      /*     mrk_lexer_advance(lexer); */
-      /*     mrk_lexer_emit(out, lexer, mrk_token_type_star_star); */
-      /*   } else { */
-      /*     // TODO match word */
-      /*   } */
-      /* default: */
-      /*   return mrk_lexer_err_unexpected_char; */
+    case '\t':
+      mrk_lexer_emit(out, lexer, mrk_token_type_tab);
+      break;
+    case '>':
+      mrk_lexer_emit(out, lexer, mrk_token_type_right_angle_bracket);
+      break;
     }
   }