From c48adb1306d7a2d69c45e841733ebbce0925191f Mon Sep 17 00:00:00 2001
From: omicron <omicron.me@protonmail.com>
Date: Tue, 1 Apr 2025 20:03:28 +0200
Subject: [PATCH] Add basic parser utilities

---
 src/parser/util.c | 35 +++++++++++++++++++++++++++++++++++
 src/parser/util.h | 25 +++++++++++++++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100644 src/parser/util.c
 create mode 100644 src/parser/util.h

diff --git a/src/parser/util.c b/src/parser/util.c
new file mode 100644
index 0000000..9b3cd18
--- /dev/null
+++ b/src/parser/util.c
@@ -0,0 +1,35 @@
+#include "util.h"
+#include "../tokenlist.h"
+
+error_t *err_parse_no_match =
+    &(error_t){.message = "parsing failed to find the correct token sequence"};
+
+parse_result_t parse_error(error_t *err) {
+    return (parse_result_t){.err = err};
+}
+
+parse_result_t parse_no_match() {
+    return parse_error(err_parse_no_match);
+}
+
+parse_result_t parse_success(ast_node_t *ast, tokenlist_entry_t *next) {
+    next = tokenlist_skip_trivia(next);
+    return (parse_result_t){.node = ast, .next = next};
+}
+
+parse_result_t parse_token(tokenlist_entry_t *current,
+                           lexer_token_id_t token_id, node_id_t ast_id,
+                           token_validator_t is_valid) {
+    if (current->token.id != token_id ||
+        (is_valid && !is_valid(&current->token)))
+        return parse_no_match();
+
+    ast_node_t *node;
+    error_t *err = ast_node_alloc(&node);
+    if (err)
+        return parse_error(err);
+    node->id = ast_id;
+    node->token_entry = current;
+
+    return parse_success(node, current->next);
+}
diff --git a/src/parser/util.h b/src/parser/util.h
new file mode 100644
index 0000000..ee5a315
--- /dev/null
+++ b/src/parser/util.h
@@ -0,0 +1,25 @@
+#ifndef INCLUDE_PARSER_UTIL_H_
+#define INCLUDE_PARSER_UTIL_H_
+
+#include "../ast.h"
+#include "../error.h"
+#include "../tokenlist.h"
+
+typedef struct parse_result {
+    error_t *err;
+    tokenlist_entry_t *next;
+    ast_node_t *node;
+} parse_result_t;
+
+typedef bool (*token_validator_t)(lexer_token_t *);
+
+parse_result_t parse_error(error_t *err);
+parse_result_t parse_no_match();
+parse_result_t parse_success(ast_node_t *ast, tokenlist_entry_t *next);
+parse_result_t parse_token(tokenlist_entry_t *current,
+                           lexer_token_id_t token_id, node_id_t ast_id,
+                           token_validator_t is_valid);
+
+extern error_t *err_parse_no_match;
+
+#endif // INCLUDE_PARSER_UTIL_H_