feat: add sematic analysis

6 files changed, 138 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index a908a73..90b3c82 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,6 +2,7 @@
 
 #include "io/file.h"
 #include "cli/args.h"
+#include "sema/sema.h"
 #include "lexer/lexer.h"
 #include "codegen/nasm.h"
 #include "parser/parser.h"
@@ -36,6 +37,13 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
+	if (!analyze_program(&program))
+	{
+		free_program(&program);
+		free_file(&source);
+		return 1;
+	}
+
 	FILE* out = stdout;
 	if (args.output_path != NULL)
 	{
diff --git a/src/sema/sema.c b/src/sema/sema.c
new file mode 100644
index 0000000..99ec4f1
--- /dev/null
+++ b/src/sema/sema.c
@@ -0,0 +1,73 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "sema/sema.h"
+
+static bool names_equal(struct Token a, struct Token b)
+{
+	return a.length == b.length && memcmp(a.start, b.start, a.length) == 0;
+}
+
+static bool check_duplicate_names(struct Program* program)
+{
+	size_t count = program->const_count + program->data_count + program->proc_count;
+	if (count == 0)
+		return true;
+
+	struct Token* names = malloc(count * sizeof(struct Token));
+	size_t n = 0;
+	for (size_t i = 0; i < program->const_count; i += 1)
+	{
+		names[n] = program->consts[i].name;
+		n += 1;
+	}
+	for (size_t i = 0; i < program->data_count; i += 1)
+	{
+		names[n] = program->data_decls[i].name;
+		n += 1;
+	}
+	for (size_t i = 0; i < program->proc_count; i += 1)
+	{
+		names[n] = program->procs[i].name;
+		n += 1;
+	}
+
+	bool ok = true;
+	for (size_t i = 0; i < count; i += 1)
+		for (size_t j = 0; j < i; j += 1)
+			if (names_equal(names[i], names[j]))
+			{
+				fprintf(stderr, "error: line %u: '%.*s' is already defined\n",
+					names[i].line, (int)names[i].length, names[i].start);
+				ok = false;
+			}
+
+	free(names);
+	return ok;
+}
+
+static bool check_entry_point(struct Program* program)
+{
+	for (size_t i = 0; i < program->proc_count; i += 1)
+	{
+		struct Token name = program->procs[i].name;
+		if (name.length == 4 && memcmp(name.start, "main", 4) == 0)
+			return true;
+	}
+
+	fprintf(stderr, "error: no 'main' procedure defined\n");
+	return false;
+}
+
+bool analyze_program(struct Program* program)
+{
+	bool ok = true;
+
+	if (!check_duplicate_names(program))
+		ok = false;
+	if (!check_entry_point(program))
+		ok = false;
+
+	return ok;
+}
diff --git a/src/sema/sema.h b/src/sema/sema.h
new file mode 100644
index 0000000..e015f41
--- /dev/null
+++ b/src/sema/sema.h
@@ -0,0 +1,7 @@
+#pragma once
+
+#include <stdbool.h>
+
+#include "parser/ast.h"
+
+bool analyze_program(struct Program* program);
diff --git a/tests/main.c b/tests/main.c
index f0caf52..dfd3ed9 100644
--- a/tests/main.c
+++ b/tests/main.c
@@ -8,6 +8,7 @@ int main(void)
 
 	run_lexer_tests(&context);
 	run_parser_tests(&context);
+	run_sema_tests(&context);
 	run_codegen_tests(&context);
 
 	printf("\n%d checks, %d failure(s)\n", context.checks, context.failures);
diff --git a/tests/sema_test.c b/tests/sema_test.c
new file mode 100644
index 0000000..a1946d9
--- /dev/null
+++ b/tests/sema_test.c
@@ -0,0 +1,48 @@
+#include <stdbool.h>
+
+#include "parser/parser.h"
+#include "sema/sema.h"
+#include "tests.h"
+
+static bool analyze_source(const char* source)
+{
+	struct Lexer lexer = create_lexer(source);
+	struct Program program;
+	if (!parse_program(&lexer, &program))
+	{
+		free_program(&program);
+		return false;
+	}
+
+	bool ok = analyze_program(&program);
+	free_program(&program);
+	return ok;
+}
+
+static void test_valid_program(struct TestContext* context)
+{
+	check(context, analyze_source("const N = 1\ndata msg = \"hi\"\nproc main\n{\nsyscall\n}\n"));
+}
+
+static void test_missing_main(struct TestContext* context)
+{
+	check(context, !analyze_source("proc helper\n{\nsyscall\n}\n"));
+}
+
+static void test_duplicate_const(struct TestContext* context)
+{
+	check(context, !analyze_source("const X = 1\nconst X = 2\nproc main\n{\nsyscall\n}\n"));
+}
+
+static void test_duplicate_across_kinds(struct TestContext* context)
+{
+	check(context, !analyze_source("data foo = \"a\"\nproc foo\n{\nsyscall\n}\nproc main\n{\nsyscall\n}\n"));
+}
+
+void run_sema_tests(struct TestContext* context)
+{
+	test_valid_program(context);
+	test_missing_main(context);
+	test_duplicate_const(context);
+	test_duplicate_across_kinds(context);
+}
diff --git a/tests/tests.h b/tests/tests.h
index 32ee4a6..2caf9b3 100644
--- a/tests/tests.h
+++ b/tests/tests.h
@@ -4,4 +4,5 @@
 
 void run_lexer_tests(struct TestContext* context);
 void run_parser_tests(struct TestContext* context);
+void run_sema_tests(struct TestContext* context);
 void run_codegen_tests(struct TestContext* context);