diff options
Diffstat (limited to 'forth.c')
| -rw-r--r-- | forth.c | 280 |
1 files changed, 280 insertions, 0 deletions
@@ -0,0 +1,280 @@ +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/types.h> +#include <unistd.h> +#include <stdbool.h> + +typedef int stackitem; + +typedef struct { + int size; + int maxsize; + stackitem* start; +} stack; + +stack* newstack() { + stack* s = malloc(sizeof(stack)); + s->size = 0; + s->maxsize = 1024; + s->start = malloc(sizeof(stackitem) * s->maxsize); + return s; +} + +stackitem pop(stack* s) { + if (s->size > 0) { + s->size = s->size - 1; + stackitem si = s->start[s->size]; +// fprintf(stderr, "[popped %d from i=%d]", si,s->size); + return si; + } else { + // tried to pop empty stack + return 0; + } +} + +stackitem peek(stack* s) { + if (s->size > 0) { + return s->start[s->size - 1]; + } else { + // tried to pop empty stack + return 0; + } +} + +void dump(stack* s) { + for (int i = 0; i < s->size; i++) { + printf("%d,", s->start[i]); + } + printf("\n"); +} + + +void push(stack *s, stackitem si) { +// fprintf(stderr, "pushing %d", si); + if (s->size >= s->maxsize) { + fprintf(stderr, "Error Stack Overflow"); + exit(1); + } else { + s->start[s->size] = si; + s->size = s->size + 1; + } +} + +void add(stack *s) { + + int x = pop(s); + int y = pop(s); + // fprintf(stderr, "adding %d + %d",x,y); + push(s, x + y); +} + +void sub(stack *s) { + int x = pop(s); + int y = pop(s); + push(s, y - x); +} + +void s_dup(stack *s) { + int x = pop(s); + push(s, x); + push(s, x); +} + +typedef void (*stackop)(stack *); + + +typedef struct { + char* word; + bool isscript; + union { + stackop op; + struct { + char* script; + int scriptlen; + }; + }; +} wordop; + +#define OPTABLE_MAX_SIZE 1024 +wordop optable[OPTABLE_MAX_SIZE] = { + {"+", false, add}, + {"-", false, sub}, + {"dup", false, s_dup}, + {"dump", false, dump}, +}; +int optablelen = 4; + +const int DEFINED_FUNC_MAX_LENGTH = 1024; +const int WORD_LEN_LIMIT = 255; + +int defineop(int starti, char *input) { + char *funcscript = malloc(sizeof(char) * DEFINED_FUNC_MAX_LENGTH); + int funcscripti = 0; + char *opcode = malloc(sizeof(char) * WORD_LEN_LIMIT); + int opcodei = 0; + while (input[starti] == ' ' || input[starti] == ':') { + starti++; + } + while (input[starti] != ' ' && opcodei < WORD_LEN_LIMIT) { + opcode[opcodei++] = input[starti++]; + } + opcode[opcodei] = '\0'; + while (input[starti] != ';' && funcscripti < DEFINED_FUNC_MAX_LENGTH) { + funcscript[funcscripti++] = input[starti++]; + } + funcscript[funcscripti] = '\0'; + if (optablelen >= OPTABLE_MAX_SIZE) { + // Error + fprintf(stderr, "Error: optable reached max size, failed to create new user defined operation"); + exit(1); + } + optable[optablelen].word = opcode; //{opcode, true, funcscript}; + optable[optablelen].isscript = true; + optable[optablelen].script = funcscript; + optable[optablelen].scriptlen = funcscripti; +// fprintf(stderr, "defining op '%s' with script '%s' and length '%d'", opcode, funcscript, funcscripti); +// fprintf(stderr, "defined op %s", optable[optablelen].word); + optablelen++; + return starti; +} + +void donothing(stack* s) {} + +wordop* getop(char *word) { + for (int i = 0; i < optablelen; i++) { +// fprintf(stderr, "['%s' = '%s'?]", optable[i].word, word); + if (!strcmp(optable[i].word, word)) { + return &optable[i]; + } + } + return 0; +} + +//https://stackoverflow.com/a/58585995 +char isnumber(char *text) { + int j; + j = strlen(text); + while(j--) { + if(text[j] >= '0' && text[j] <= '9') + continue; + return 0; + } + return 1; +} + +void eval(stack* s, int len, char* line); + +void exec(stack *s, char *word) { + if (!strcmp(word, "pop") || !strcmp(word, ".")) { + printf("%d\n", pop(s)); + return; + } else if (!strcmp(word, "peek")) { + printf("%d\n", peek(s)); + return; + } +// fprintf(stderr, "[looking up op %s]", word); + wordop* op = getop(word); + if (op) { + +// fprintf(stderr, "[op %s]", op->word); + if (op->isscript) { +// fprintf(stderr, "eval: %s (len: %d)", op->script, op->scriptlen); + eval(s, op->scriptlen, op->script); + } else { + op->op(s); + } + return; + } + if (isnumber(word)) { + // fprintf(stderr, "[number %s]", word); + push(s, atoi(word)); + return; + } +} + +//void eval(int scriptlen, char* script) { +void eval(stack* s, int len, char* line) { + char word[WORD_LEN_LIMIT]; + int wordi = 0; + for (int i = 0; i < len; i++) { + + // end of input is \n, char after end of input is \0 + if (line[i] == '\0') { + return; + } + +// printf("i%d - %c;", i, line[i]); + if (line[i] != ' ' && + line[i] != '\n' && wordi < WORD_LEN_LIMIT - 1) { + if (line[i] == ':') { + i = defineop(i, line); + wordi = 0; + } else { + word[wordi++] = line[i]; + } + } else { // end of word + if (wordi > 0) { // don't exec an empty string + word[wordi] = '\0'; + exec(s, word); + } + // start new word + wordi = 0; + } + } +} + +int main(int argc, char** argv) { + stack* s = newstack(); + + for (int i = 1; i < argc; i++) { + exec(s, argv[i]); + } + +// char ch; +// char word[WORD_LEN_LIMIT]; +// int wordi; +// while (read(STDIN_FILENO, &ch, 1) > 0) { +// if (ch != ' ' && wordi < WORD_LEN_LIMIT) { +// word[wordi++] = ch; +// } else { +// word[wordi] = '\0'; +// exec(s, word); +// wordi = 0; +// } +// } +// + char *line = NULL; + size_t len = 0; + ssize_t read; + + while ((read = getline(&line, &len, stdin)) != -1) { + // printf("%s",line); + // printf("%d",(int)len); + eval(s, len, line); + } + + // push(s, 8); + // push(s, 9); + + // printf("%d\n", pop(s)); + // printf("%d\n", pop(s)); + // printf("%d\n", pop(s)); + // printf("%d\n", pop(s)); + // push(s, 8); + // push(s, 9); + // add(s); + // dup(s); + // printf("%d\n", pop(s)); + // push(s, 1); + // sub(s); + // printf("%d\n", peek(s)); + // printf("%d\n", pop(s)); + + // stackop op = getop("+"); + // if (op) { + // op(s); + // } + + +} |