From 3a9a1921fe7a56cefe6650529a2572e9a8debc98 Mon Sep 17 00:00:00 2001
From: Felix Perktold <Felix.Perktold@student.uibk.ac.at>
Date: Tue, 23 Dec 2025 12:47:31 +0100
Subject: multiline support in REPL, tab completion for environment (no special
 forms yet)

---
 main.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 77 insertions(+), 9 deletions(-)

(limited to 'main.c')

diff --git a/main.c b/main.c
index 5a7c893..3f851a8 100644
--- a/main.c
+++ b/main.c
@@ -8,7 +8,6 @@
 
 env *global_env = NULL;
 
-
 void eval_file(const char *filename) {
 	FILE *f = fopen(filename, "r");
 	if (!f) {
@@ -16,15 +15,63 @@ void eval_file(const char *filename) {
 		return;
 	}
 
+	int parens = 0;
 	char line[1024];
+	char buffer[4096] = "";
 	while (fgets(line, sizeof(line), f)) {
 		if (*line == '\n' || *line == ';') continue; // skip empty lines or comments
-		yy_scan_string(line);
-		yyparse();
+		for (char *c = line; *c != '\0'; c++) {
+			if (*c == '(') {
+				parens++;
+			} else if (*c == ')') {
+				parens--;
+			}
+		}
+		//append line to buffer
+		strcat(buffer, line);
+		strcat(buffer, "\n");
+		if (parens <= 0) {
+			//if parens are balanced: parse
+			yy_scan_string(buffer);
+			yyparse();
+			//reset buffer
+			buffer[0] = '\0';
+		}
 	}
 	fclose(f);
 }
 
+char *env_token_gen(const char *text, int state) {
+	static int len;
+	static env *nth_env;
+	if (state == 0) {
+		nth_env = global_env->next;
+		len = strlen(text);
+	}
+
+	while (nth_env) {
+		const char *cur = nth_env->symbol;
+		nth_env = nth_env->next;
+
+		if (strncmp(cur, text, len) == 0) {
+			return strdup(cur);
+		}
+	}
+
+	return NULL;
+}
+
+/* Dispatch function: called by readline to get all matches */
+char **my_completion(const char *text, int start, int end) {
+    /* Prevent default filename completion */
+	rl_attempted_completion_over = 1;
+	return rl_completion_matches(text, env_token_gen);
+}
+
+void init_readline() {
+	rl_attempted_completion_function = my_completion;
+}
+
 int main(int argc, char **argv) {
 	// init global env
 	global_env = env_create(NULL);
@@ -46,13 +93,34 @@ int main(int argc, char **argv) {
 	}
 
 	// START REPL
-	char* line;
-	while ((line = readline("λ> ")) != NULL) {
-		if (*line) {
-			add_history(line);
+	init_readline();
+
+	int parens = 0;
+	char *line;
+	char buffer[4096] = "";
+	char *prompt = "λ> ";
+	while ((line = readline(prompt)) != NULL) {
+		for (char *c = line; *c != '\0'; c++) {
+			if (*c == '(') {
+				parens++;
+			} else if (*c == ')') {
+				parens--;
+			}
+		}
+		//append line to buffer
+		strcat(buffer, line);
+		if (parens <= 0) {
+			//if parens are balanced parse
+			yy_scan_string(buffer);
+			yyparse();
+			add_history(buffer);
+			//reset buffer and prompt string
+			buffer[0] = '\0';
+			prompt = "λ> ";
+		} else {
+			strcat(buffer, "\n");
+			prompt = "   ";
 		}
-		yy_scan_string(line);
-		yyparse();
 		free(line);
 	}
 	return 0;
-- 
cgit v1.2.3