main.c

/*
 * PL/0 Compiler - Main Entry Point
 *
 * Usage: pl0c [-t] [source_file]
 *   -t    Enable instruction trace
 *   file  PL/0 source file (default: read from stdin)
 *
 * Compiles PL/0 source code to bytecode and executes it.
 */

#include "pl0.h"
#include <fcntl.h>
#include <unistd.h>

/*
 * Read entire file into memory. Returns heap-allocated string.
 * Caller must free the returned pointer.
 */
static char *read_file(const char *path)
{
    FILE *fp;
    char *content;
    long size;

    if (path == NULL || strcmp(path, "-") == 0) {
        fp = stdin;
    } else {
        fp = fopen(path, "r");
        if (fp == NULL) {
            perror("fopen");
            return NULL;
        }
    }

    /* Get file size - only for regular files, not stdin */
    if (fp == stdin) {
        /* For stdin, read chunks until EOF */
        size = 0;
        size_t buf_size = 4096;
        content = malloc(buf_size);
        if (content == NULL) {
            return NULL;
        }
        size_t total_read = 0;
        char buf[256];
        while (fgets(buf, sizeof(buf), fp) != NULL) {
            size_t len = strlen(buf);
            if (total_read + len >= buf_size) {
                buf_size *= 2;
                char *new_content = realloc(content, buf_size);
                if (new_content == NULL) {
                    free(content);
                    return NULL;
                }
                content = new_content;
            }
            memcpy(content + total_read, buf, len);
            total_read += len;
        }
        content[total_read] = '\0';
        return content;
    }

    fseek(fp, 0, SEEK_END);
    size = ftell(fp);
    fseek(fp, 0, SEEK_SET);

    /* Allocate buffer + null terminator */
    content = malloc(size + 1);
    if (content == NULL) {
        perror("malloc");
        fclose(fp);
        return NULL;
    }

    /* Read entire file */
    size_t read_size = fread(content, 1, size, fp);
    content[read_size] = '\0';

    fclose(fp);

    return content;
}

/*
 * Print usage information.
 */
static void usage(const char *prog)
{
    printf("PL/0 Compiler v1.0\n");
    printf("Usage: %s [-t] [source_file]\n", prog);
    printf("  -t    Enable instruction trace\n");
    printf("  file  PL/0 source file (default: read from stdin)\n");
}

int main(int argc, char *argv[])
{
    const char *filename = NULL;
    int trace = 0;

    /* Parse arguments */
    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i], "-t") == 0) {
            trace = 1;
        } else if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
            usage(argv[0]);
            return 0;
        } else if (argv[i][0] != '-') {
            filename = argv[i];
        } else {
            fprintf(stderr, "Unknown option: %s\n", argv[i]);
            usage(argv[0]);
            return 1;
        }
    }

    /* Read source file */
    char *source = read_file(filename);
    if (source == NULL) {
        return 1;
    }

    /* Compile */
    Code code;
    SymbolTable symbols;

    int result = compile(source, &code, &symbols);
    free(source);

    if (result < 0) {
        return 1;
    }

    printf("Compiled successfully (%d instructions)\n", code.code_count);

    /* Run */
    return run(&code, trace);
}