From ab8568dcb105d5c34f42d7587bd649e0cb3563b7 Mon Sep 17 00:00:00 2001
From: icst <icst@no.email>
Date: Fri, 21 Jun 2024 20:21:42 -0400
Subject: [PATCH] Pass indication of an error back up to avoid confusing EOFs
 and errors in some corner cases

---
 lapis.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/lapis.c b/lapis.c
index 8fec0c5..ed9ba26 100644
--- a/lapis.c
+++ b/lapis.c
@@ -103,9 +103,9 @@ void lapis_token_free(lapis_token_t *token) {
     }
 }
 
-lapis_node_t *lapis_parse_expr(size_t *nnodes, FILE *f);
+lapis_node_t *lapis_parse_expr(int64_t *nnodes, FILE *f);
 
-lapis_token_t *lapis_parse_tokens(size_t *ntokens, FILE *f) {
+lapis_token_t *lapis_parse_tokens(int64_t *ntokens, FILE *f) {
 
     size_t num_tokens = 0;
     lapis_token_t *tokens = NULL;
@@ -124,11 +124,12 @@ lapis_token_t *lapis_parse_tokens(size_t *ntokens, FILE *f) {
             while (1) {
 
                 //puts("++++++++++");
-                size_t nnodes;
+                int64_t nnodes;
                 lapis_node_t *nodes = lapis_parse_expr(&nnodes, f);
                 //puts("----------");
 
-                if ( nodes == 0 ) break;
+                if ( nnodes < 0 ) goto ERROR;
+                if ( nnodes == 0 ) break;
 
                 //printf("%lu: ", nstmts);
                 //lapis_node_print(nodes, nnodes-1);
@@ -321,19 +322,27 @@ ERROR:
         for (size_t n=0; n < num_tokens; n++) lapis_token_free(&tokens[n]);
         free(tokens);
     }
+    *ntokens = -1;
     return NULL;
 }
 
-lapis_node_t *lapis_parse_expr(size_t *nnodes, FILE *f) {
+lapis_node_t *lapis_parse_expr(int64_t *nnodes, FILE *f) {
 
     lapis_token_t *tokens = NULL;
     int64_t *oper_priorities = NULL;
     uint8_t *oper_arg_form = NULL;
     lapis_node_t *nodes = NULL;
 
-    size_t ntokens=0;
+    int64_t ntokens=0;
     tokens = lapis_parse_tokens(&ntokens, stdin);
-    if ( tokens == NULL ) goto ERROR;
+
+    if ( ntokens < 0 ) goto ERROR;
+
+    if ( tokens == NULL ) {
+        // likely EOF; exit cleanly
+        *nnodes = 0;
+        return NULL;
+    }
 
     oper_priorities = malloc( ntokens * sizeof(int64_t) );
     if ( oper_priorities == NULL ) goto ERROR;
@@ -673,13 +682,13 @@ ERROR:
     if ( oper_arg_form != NULL ) free( oper_arg_form );
     if ( nodes != NULL ) free( nodes );
 
-    *nnodes = 0;
+    *nnodes = -1;
     return NULL;
 }
 
 int main() {
 #if 0
-    size_t ntokens=0;
+    int64_t ntokens=0;
     lapis_token_t *tokens = lapis_parse_tokens(&ntokens, stdin);
 
     printf("Tokens (%lu):\n", ntokens);
@@ -704,9 +713,14 @@ int main() {
 #else
     while (1) {
 
-        size_t nnodes;
+        int64_t nnodes;
         lapis_node_t *nodes = lapis_parse_expr(&nnodes, stdin);
 
+        if ( nnodes < 0 ) {
+            fputs("Error occured while parsing expression!\n", stderr);
+            return 1;
+        }
+
         if ( nnodes == 0 ) break;
 
         lapis_node_print(nodes, nnodes-1);