From 036943d920182fe2c50e00cee2c667f6686e464a Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Fri, 8 Oct 2021 15:06:54 +0200
Subject: Change parser to work consuming tokens

---
 src/bootstrap/main.c | 51 ++++++++++++++++++++++++++++++---------------------
 1 file changed, 30 insertions(+), 21 deletions(-)

(limited to 'src/bootstrap')

diff --git a/src/bootstrap/main.c b/src/bootstrap/main.c
index a0b0f69..fad3333 100755
--- a/src/bootstrap/main.c
+++ b/src/bootstrap/main.c
@@ -153,6 +153,17 @@ tokenize(StringView sv) {
     return (Tokens){.start = (StringView *)&tokens_buf, .n = n};
 }
 
+StringView *
+consume_token(Tokens *tokens) {
+    if (tokens->n == 0) {
+        return NULL;
+    }
+    StringView *ret = tokens->start;
+    tokens->start = &tokens->start[1];
+    tokens->n--;
+    return ret;
+}
+
 typedef enum ObjectType {
     OBJ_TYPE_FIXNUM,
     OBJ_TYPE_BOOL,
@@ -278,27 +289,27 @@ token_is_fixnum(StringView token) {
 #define FALSE_TOKEN (StringView){"false", 5}
 
 Object *
-build_ast(Tokens tokens) {
+build_ast(Tokens *tokens) {
     // DEBUG: Printing tokens.
-    // printf("N_TOKENS: %ld\n", tokens.n);
-    // for (size_t i = 0; i < tokens.n; i++) {
+    // printf("N_TOKENS: %ld\n", tokens->n);
+    // for (size_t i = 0; i < tokens->n; i++) {
     //     printf("TOKEN: ");
-    //     sv_write(tokens.start[i]);
-    //     printf("\tN: %ld", tokens.start[i].n);
+    //     sv_write(tokens->start[i]);
+    //     printf("\tN: %ld", tokens->start[i].n);
     //     printf("\n");
     // }
 
     // TODO: Report error if we haven't consumed all the tokens?
-    for (size_t i = 0; i < tokens.n; i++) {
-        StringView token = tokens.start[i];
+    while (tokens->n > 0) {
+        StringView *token = consume_token(tokens);
 
         // OBJ_TYPE_FIXNUM
-        if (token_is_fixnum(token)) {
+        if (token_is_fixnum(*token)) {
             // Convert token to fixnum.
             ssize_t num = 0;
             int sign = 1;
-            for (size_t i = 0; i < token.n; i++) {
-                char c = token.start[i];
+            for (size_t i = 0; i < token->n; i++) {
+                char c = token->start[i];
                 if (c == '-') {
                     sign = -1;
                     continue;
@@ -309,35 +320,32 @@ build_ast(Tokens tokens) {
         }
 
         // OBJ_TYPE_BOOL
-        if (sv_equal(token, TRUE_TOKEN)) {
+        if (sv_equal(*token, TRUE_TOKEN)) {
             return make_boolean(true);
         }
-        if (sv_equal(token, FALSE_TOKEN)) {
+        if (sv_equal(*token, FALSE_TOKEN)) {
             return make_boolean(false);
         }
 
         // OBJ_TYPE_LIST
-        if (token.start[0] == ')') {
+        if (token->start[0] == ')') {
             return NULL;
         }
-        if (token.start[0] == '(') {
-            if ((i + 1) < tokens.n && tokens.start[i + 1].start[0] == ')') {
+        if (token->start[0] == '(') {
+            if (tokens->n > 0 && tokens->start[0].start[0] == ')') {
                 return make_empty_list();
             }
 
             Object *list = make_empty_list();
             Object *next_obj = NULL;
-            while (((i + 1) < tokens.n) && (next_obj = build_ast((Tokens){&tokens.start[i + 1], tokens.n - i - 1})) != NULL) {
+            while (tokens->n > 0 && (next_obj = build_ast(tokens)) != NULL) {
                 push_obj_to_list(list, &next_obj);
-                // FIXME: must consume tokens instead, otherwise recursive lists
-                // will not work.
-                i++;
             }
             return list;
         }
 
         // OBJ_TYPE_SYMBOL
-        return make_symbol(token.start, token.n);
+        return make_symbol(token->start, token->n);
     }
 
     return NULL;
@@ -393,7 +401,8 @@ main(void) {
     while (true) {
         printf(REPL_PROMPT);
         StringView line = read_line();
-        Object *ast = build_ast(tokenize(line));
+        Tokens tokens = tokenize(line);
+        Object *ast = build_ast(&tokens);
         if (ast) {
             display(ast);
             printf("\n");
-- 
cgit v1.2.1