read.c

#include "read.h"

char code[BUFSIZ];

Obj read_code(void) {
    while (!lib_loaded()) {
        char* lib_code = load_library();
        Obj result = parse(lib_code);
        return result;
    }

    if (LIB) toggle_LIB();

    input_prompt();

    while (isSpecial(code)) {
        if (isFlag(code)) {
            switch_flag(code);
            print_flags();
        } else if (isHelp(code))
            print_help();
        input_prompt();
    }

    if (DEBUG) printf("\nLISP CODE: %s\n", code);

    Obj result = parse(code);
    return result;
}

/* input prompt */

void input_prompt(void) {
    print_prompt();
    get_input();

    if (isIrregular(code)) {
        if (badSyntax(code)) printf("Bad syntax! Try again!\n");
        input_prompt();
    }
}

void print_prompt(void) {
    NL;
    printf("lispinc >>> ");
}

/* NB: fgets add an extra newline at the end of input */
void get_input(void) {
    fgets(code, BUFSIZ, stdin);
    // code[strlen(code) - 1] = '\0';
}

bool isIrregular(char* code) { return badSyntax(code) || isEnter(code); }

bool isEnter(char* code) { return streq(code, "\n"); }

// other bad syntax conditions can be added later
bool badSyntax(char* code) { return !parens_balanced(code); }

bool parens_balanced(char* code) {
    int op = 0;
    int cp = 0;
    int len = strlen(code);

    for (int i = 0; i < len; i++) {
        if (OPENPAREN(code[i])) op++;
        if (CLOSEPAREN(code[i])) cp++;
    }

    return op == cp;
}

/* check for user commands (see flags.h) */

int isSpecial(char* code) {
    if (DEBUG) printf("isSpecial\n");

    return isFlag(code) || isHelp(code);  // || isQuit(code);
}

// inelegant
int isFlag(char* code) {
    if (DEBUG) printf("isFlag\n");

    return streq(code, DEBUG_COMMAND) || streq(code, DEMO_COMMAND)
           || streq(code, INFO_COMMAND) || streq(code, REPL_COMMAND)
           || streq(code, STATS_COMMAND) || streq(code, STEP_COMMAND)
           || streq(code, TAIL_COMMAND);
}

int isHelp(char* code) {
    if (DEBUG) printf("isHelp\n");

    return streq(code, HELP_COMMAND);
}

// bool isQuit(char* code) {
//          if (DEBUG) printf("isQuit\n");
//  return streq(code, _QUIT);
// }

int streq(char* str1, char* str2) { return strcmp(str1, str2) == 0; }