add: parse proc declarations

1 files changed, 86 insertions, 0 deletions

diff --git a/src/parser/parser.c b/src/parser/parser.c
index 4fb85ef..acd4b7a 100644
--- a/src/parser/parser.c
+++ b/src/parser/parser.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <stdlib.h>
 
 #include "parser/parser.h"
 
@@ -27,6 +28,15 @@ static void error_at(struct Parser* parser, struct Token token, const char* mess
 	parser->had_error = true;
 }
 
+static bool match_token(struct Parser* parser, enum TokenType type)
+{
+	if (!check(parser, type))
+		return false;
+
+	advance_parser(parser);
+	return true;
+}
+
 static bool consume(struct Parser* parser, enum TokenType type, const char* message)
 {
 	if (check(parser, type))
@@ -77,6 +87,76 @@ static bool parse_data(struct Parser* parser, struct Program* program)
 	return true;
 }
 
+static bool parse_params(struct Parser* parser, struct ProcDecl* proc)
+{
+	if (check(parser, TOKEN_RIGHT_PAREN))
+		return true;
+
+	do
+	{
+		struct Param param;
+
+		if (!consume(parser, TOKEN_IDENTIFIER, "expected parameter name"))
+			return false;
+		param.name = parser->previous;
+
+		if (!consume(parser, TOKEN_COLON, "expected ':' after parameter name"))
+			return false;
+
+		if (!consume(parser, TOKEN_IDENTIFIER, "expected register after ':'"))
+			return false;
+		param.reg = parser->previous;
+
+		add_param(proc, param);
+	}
+	while (match_token(parser, TOKEN_COMMA));
+
+	return true;
+}
+
+static bool parse_proc(struct Parser* parser, struct Program* program)
+{
+	struct ProcDecl decl = create_proc();
+
+	if (!consume(parser, TOKEN_IDENTIFIER, "expected procedure name after 'proc'"))
+		goto error;
+	decl.name = parser->previous;
+
+	if (match_token(parser, TOKEN_LEFT_PAREN))
+	{
+		if (!parse_params(parser, &decl))
+			goto error;
+		if (!consume(parser, TOKEN_RIGHT_PAREN, "expected ')' after parameters"))
+			goto error;
+	}
+
+	if (!consume(parser, TOKEN_LEFT_BRACE, "expected '{' to begin procedure body"))
+		goto error;
+
+	// TODO: parse body statements; for now skip the braced block
+	int depth = 1;
+	while (depth > 0)
+	{
+		if (check(parser, TOKEN_EOF))
+		{
+			error_at(parser, parser->current, "unterminated procedure body");
+			goto error;
+		}
+		if (check(parser, TOKEN_LEFT_BRACE))
+			depth += 1;
+		else if (check(parser, TOKEN_RIGHT_BRACE))
+			depth -= 1;
+		advance_parser(parser);
+	}
+
+	add_proc(program, decl);
+	return true;
+
+error:
+	free(decl.params);
+	return false;
+}
+
 bool parse_program(struct Lexer* lexer, struct Program* out)
 {
 	struct Parser parser;
@@ -100,6 +180,12 @@ bool parse_program(struct Lexer* lexer, struct Program* out)
 			if (!parse_data(&parser, out))
 				return false;
 		}
+		else if (check(&parser, TOKEN_PROC))
+		{
+			advance_parser(&parser);
+			if (!parse_proc(&parser, out))
+				return false;
+		}
 		else
 		{
 			error_at(&parser, parser.current, "expected a top-level declaration");