lang.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <ctype.h>

struct node {
  double x;
  int subscript;
  struct node *next;
} *head = NULL, *root = NULL;

struct node *list_create()
{
  root = (struct node*)malloc(sizeof(struct node));
  head = root;
  head->next = NULL;
  return root;
}
int list_length()
{
  int cnt = 0;
  struct node ptr = *root;
  while (ptr.next != NULL) {
    ptr = *ptr.next;
    ++cnt;
  }
  return cnt;
}
struct node *list_get(int location)
{
  struct node *ptr;
  ptr = root;
  for (int ptr_location = 0; ptr_location < location; ++ptr_location)
    ptr = ptr->next;
  return ptr;
}
struct node *list_push(double x)
{
  head->next = (struct node*)malloc(sizeof(struct node));
  int old_subscript = head->subscript;
  head = head->next;
  head->next = NULL;
  head->x = x;
  head->subscript = old_subscript + 1;
  return head;
}
struct node *list_pop()
{
  if(list_length() < 1) return NULL;
  struct node *prev = list_get(head->subscript - 1);
  head = prev;
  struct node *old_head_next = (struct node*)malloc(sizeof(struct node));
  old_head_next->x = head->next->x;
  old_head_next->subscript = head->next->subscript;
  free(head->next);
  head->next = NULL;
  return old_head_next;
}
void list_clear()
{
  int length = list_length();
  for (int i = 0; i < length; ++i)
    list_pop();
}
struct node *list_copy()
{
  return list_push(head->x);
}
struct node *list_root()
{
  return root;
}
struct node *list_head()
{
  return head;
}

struct node *list_add()
{
  if (list_length() < 2) return NULL;
  struct node *operand0 = list_pop();
  struct node *operand1 = list_pop();
  return list_push(operand1->x + operand0->x);
}
struct node *list_sub()
{
  if (list_length() < 2) return NULL;
  struct node *operand0 = list_pop();
  struct node *operand1 = list_pop();
  return list_push(operand1->x - operand0->x);
}
struct node *list_mul()
{
  if (list_length() < 2) return NULL;
  struct node *operand0 = list_pop();
  struct node *operand1 = list_pop();
  return list_push(operand1->x * operand0->x);
}
struct node *list_div()
{
  if (list_length() < 2) return NULL;
  struct node *operand0 = list_pop();
  struct node *operand1 = list_pop();
  return list_push(operand1->x / operand0->x);
}
struct node *list_pow()
{
  if (list_length() < 2) return NULL;
  struct node *operand0 = list_pop();
  struct node *operand1 = list_pop();
  return list_push(pow(operand1->x, operand0->x));
}
struct node *head_out_char()
{
  if (list_length() < 1) return NULL;
  printf("%c\n", (int)head->x);
  return list_pop();
}
struct node *head_out_float()
{
  if (list_length() < 1) return NULL;
  printf("%f\n", head->x);
  return list_pop();
}
struct node *list_eq()
{
  if (list_length() < 2) return NULL;
  struct node *operand0 = list_pop();
  struct node *operand1 = list_pop();
  return list_push(operand0->x == operand1->x);
}
struct node *list_more()
{
  if (list_length() < 2) return NULL;
  struct node *operand0 = list_pop();
  struct node *operand1 = list_pop();
  return list_push(operand0->x == operand1->x);
}
struct node *list_less()
{
  if (list_length() < 2) return NULL;
  struct node *operand0 = list_pop();
  struct node *operand1 = list_pop();
  return list_push(operand0->x == operand1->x);
}
char list_input()
{
  char input;
  printf(">>> ");
  scanf("%s", &input);
  return input;
}
void list_print()
{
  struct node ptr = *root;
  int cnt = 0;
  while (ptr.next != NULL) {
    printf("%f", ptr.next->x);
    ptr = *ptr.next;
    if (ptr.next != NULL) printf(", ");
    ++cnt;
  }
  if (cnt > 0) printf("\n");
}
struct node *list_operate_binary(char operation){
  if (list_length() < 2) return NULL;
  struct node *operand0 = list_pop();
  struct node *operand1 = list_pop();
  switch(operation){
  case '+':
    return list_push(operand1->x + operand0->x);
  case '-':
    return list_push(operand1->x - operand0->x);
  case '*':
    return list_push(operand1->x * operand0->x);
  case '/':
    return list_push(operand1->x / operand0->x);
  case '^':
    return list_push(pow(operand1->x, operand0->x));
  case '=':
    return list_push(operand1->x == operand0->x);
  case '>':
    return list_push(operand1->x > operand0->x);
  case '<':
    return list_push(operand1->x < operand0->x);
  default:
    return NULL;
  }
}
struct node *parse(char token)
{
  if (isdigit(token))
    return list_push(token - '0');
  if (isalpha(token))
    return list_push(token);
  switch (token) {
  case '+':
    return list_add();
  case '-':
    return list_sub();
  case '*':
    return list_mul();
  case '/':
    return list_div();
  case '^':
    return list_pow();
  case '.':
    return head_out_char();
  case ':':
    return head_out_float();
  case ',':
    return list_pop();
  case '@':
    list_clear();
    return NULL;
  case '"':
    return parse(list_input());
  case '=':
    return list_eq();
  case '>':
    return list_more();
  case '<':
    return list_less();
  case '#':
    list_print();
    return NULL;
  case '_':
    return list_copy();
  default:
    return NULL;
  }
}
struct node *multi_parse(char *tokens)
{
  struct node *ret;
  struct node *temp;
  for (int i = 0; i < strlen(tokens); i++)
    if ((temp = parse(tokens[i])) != NULL) ret = temp;
  if (ret != NULL) list_print();
  return ret;
}
int main(int argc, char **argv)
{
  //list_create();
  root = (struct node*)malloc(sizeof(struct node));
  head = root;
  if (argc < 2){
    printf("Usage: ./<program> -[h|i|e] [file]\n");
    exit(1);
  }
  if (strcmp(argv[1], "-e") == 0) {
    if (argc != 3) {
      printf("Usage: ./<program> -e <expression>\n");
      exit(1);
    }
    char *expression = argv[2];
    for (int i = 0; i < argc - 2; i++)
      multi_parse(&expression[i]);
  } else if (argc == 2) {
    if (strcmp(argv[1], "-i") == 0) {
      printf("List language interactive prompt\nPress control-C to exit\n");
      while (1) {
	char input[50];
	printf(">> ");
	scanf("%49s", input);
	multi_parse(input);
      }
    } else {
      FILE *file;
      file = fopen(argv[1], "r");
      if(file == 0) {
	printf("Failed to open file\n");
	return 1;
      } else {
	int char_at_pt = fgetc(file);
	do {
	  parse((char)char_at_pt);
	} while((char_at_pt = fgetc(file)) != EOF);
	fclose(file);
      }
    }
  }
  return 0;
}

Options.cpp

#include <iostream>
#include <fstream>

void handle_args(int argc, char **argv) {
    if (argc < 2){
        help_message();
        return 1;
    }
    else {
        handle_options(argv[1]);
    }
}

void help_message() {
    std::cout << "Usage: ./<program> -[h|i] [file]\n";
}

void shell() {
    std::cout << "List language interactive prompt\nPress control-C to exit\n";
    while (true) {
	    std::string input;
	    std::cout << ">> ";
	    std::cin >> input;
	    parse(input);
    }
}

void read_file(char *filename) {
    std::string line;
    ifstream file(filename);
    
    if (myfile.is_open()) {
        while (getline(file, line)) {
            parse(line);
        }
        myfile.close();
    }
    else {
        std::cout << "Failed to open file \"" << filename << "\"\n";
    }
}

void handle_options(char *option) {
    if (strcmp(option, "-h") == 0) {
        help_message();
    }
    else if (strcmp(option, "-i") == 0) {
        shell();
    }
    else {
        read_file(option);
    }
}