feat(cli): More CLI stuff, idk

1 files changed, 157 insertions, 4 deletions

diff --git a/src/cli/main.c b/src/cli/main.c
index 4d96aa2..db42a14 100644
--- a/src/cli/main.c
+++ b/src/cli/main.c
@@ -1,13 +1,166 @@
 #include "../core/state.h"
+#include "../core/interpret.h"
 
+#include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <errno.h>
+
+int read_file(const char *file_path, char **out_buffer, size_t *out_length) {
+	assert(out_buffer != NULL && *out_buffer == NULL);
+	assert(file_path != NULL);
+
+	const size_t CHUNK_SIZE =  1024;
+
+	FILE *fp = fopen(file_path, "r");
+	if (fp == NULL) {
+		return -1;
+	}
+
+	char *buffer = NULL;
+	size_t allocated = 0;
+	size_t used = 0;
+	while (true) {
+		// Grow buffer, if needed.
+		if (used + CHUNK_SIZE > allocated) {
+			// Grow exponentially to guarantee O(log(n)) performance.
+			allocated = (allocated == 0) ? CHUNK_SIZE : allocated * 2;
+
+			// Overflow check. Some ANSI C compilers may optimize this away, though.
+			if (allocated <= used) {
+				free(buffer);
+				fclose(fp);
+				errno = EOVERFLOW;
+				return -1;
+			}
+
+			char *temp = realloc(buffer, allocated);
+			if (temp == NULL) {
+				int old_errno = errno;
+				free(buffer); // free() may not set errno
+				fclose(fp);   // fclose() may set errno
+				errno = old_errno;
+				return -1;
+			}
+			buffer = temp;
+		}
+
+		size_t nread = fread(buffer + used, 1, CHUNK_SIZE, fp);
+		if (nread == 0) {
+			// End-of-file or errnor has occured.
+			// FIXME: Should we be checking (nread < CHUNK_SIZE)?
+			//        https://stackoverflow.com/a/39322170
+			break;
+		}
+		used += nread;
+	}
+
+	if (ferror(fp)) {
+		int old_errno = errno;
+		free(buffer); // free() may not set errno
+		fclose(fp);   // fclose() may set errno
+		errno = old_errno;
+		return -1;
+	}
+
+	// Reallocate to optimal size.
+	char *temp = realloc(buffer, used + 1);
+	if (temp == NULL) {
+		int old_errno = errno;
+		free(buffer); // free() may not set errno
+		fclose(fp);   // fclose() may set errno
+		errno = old_errno;
+		return -1;
+	}
+	buffer = temp;
+
+        // Null-terminate the buffer. Note that buffers may still contain \0,
+	// so strlen(buffer) == length may not be true.
+        buffer[used] = '\0';
+
+	// Return buffer.
+	*out_buffer = buffer;
+	if (out_length != NULL) {
+		*out_length = used;
+	}
+	fclose(fp);
+	return 0;
+}
+
+static void run_file(SandState *S, const char *filename) {
+	char *source = NULL;
+	size_t source_length = 0;
+	if (read_file(filename, &source, &source_length) < 0) {
+		fprintf(stderr, "Error reading %s: %s\n", filename, strerror(errno));
+		exit(74);
+	}
+
+	SandInterpretResult result = sand_interpret(S, filename, source, source_length);
+	free(source); // At this point it should be okay to invalidate all references to the source code.
+
+	if (result == SAND_INTERPRET_COMPILE_ERROR) {
+		exit(65);
+	} else if (result == SAND_INTERPRET_RUNTIME_ERROR) {
+		exit(70);
+	}
+}
+
+static void repl(SandState *S) {
+	char *line = NULL;
+	size_t line_length = 0;
+
+	unsigned prompt_nr = 1;
+
+	while (true) {
+		printf("> ");
+		fflush(stdout);
+
+		// At this point the memory at `line` is reused, invalidating all existing references.
+		if (getline(&line, &line_length, stdin) < 0) {
+			fputc('\n', stdout);
+			break; // No more input - leave REPL loop.
+		}
+
+		// We need a dummy filename.
+		char filename[64];
+		snprintf(filename, sizeof(filename), "<repl %u>", prompt_nr);
+		prompt_nr += 1;
+
+		sand_interpret(S, filename, line, line_length);
+	}
+}
+
+static void print_help(FILE *stream, const char *argv0) {
+	fprintf(stream, "Usage: %s <filename>\n", argv0);
+	fprintf(stream, "       %s --help\n", argv0);
+	fprintf(stream, "       %s\n\n", argv0);
+	fprintf(stream, "When called without arguments, runs a REPL.\n");
+}
+
+static void print_handler(const char *message, size_t message_length) {
+	fprintf(stderr, message, message_length);
+}
 
 int main(int argc, char *argv[]) {
-	(void)argc;
-	(void)argv;
+	SandConfig config = {
+		.print_handler = print_handler,
+	};
+	SandState state = sand_create_state(config);
 
-	printf("TODO\n");
+	if (argc == 1) {
+		repl(&state);
+	} else if (argc == 2 && strcmp(argv[1], "--help") == 0) {
+		print_help(stdout, argv[0]);
+		exit(0);
+	} else if (argc == 2) {
+		run_file(&state, argv[1]);
+	} else {
+		print_help(stderr, argv[0]);
+		exit(64);
+	}
 
-	return EXIT_SUCCESS;
+	sand_destroy_state(&state);
+	return 0;
 }