86 lines
1.8 KiB
C
86 lines
1.8 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include "expressions.h"
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#include "operations.h"
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#include "error.h"
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// Think about where to put this declaration later
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lval* builtin_op(lval* v, char* op);
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lval* lval_sexpr(void) {
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lval* v = (lval *) malloc(sizeof(lval));
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v->type = LVAL_SEXPR;
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v->count = 0;
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v->cell = NULL;
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return v;
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}
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lval* lval_qexpr(void) {
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lval* v = (lval *) malloc(sizeof(lval));
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v->type = LVAL_QEXPR;
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v->count = 0;
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v->cell = NULL;
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return v;
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}
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lval* lval_add(lval* v, lval* x) {
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v->count++;
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v->cell = (lval **) realloc(v->cell, sizeof(lval*) * v->count);
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v->cell[v->count - 1] = x;
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return v;
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}
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lval* lval_pop(lval* v, int i) {
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// Find the item at i
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lval* x = v->cell[i];
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// Shift the memory after the item i over the top
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memmove(&v->cell[i], &v->cell[i + 1], sizeof(lval*) * (v->count - i - 1));
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// Decrease the count of items in the list
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v->count--;
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// Reallocate the memory used
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v->cell = (lval **) realloc(v->cell, sizeof(lval*) * v->count);
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return x;
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}
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lval* lval_take(lval* v, int i) {
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lval* x = lval_pop(v, i);
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lval_del(v);
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return x;
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}
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lval* lval_eval_sexpr(lval* v) {
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// Evaluate children
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for (int i = 0; i < v->count; i++) {
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v->cell[i] = lval_eval(v->cell[i]);
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}
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// Error checking [If there's an error, return it]
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for (int i = 0; i < v->count; i++) {
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if (v->cell[i]->type == LVAL_ERR) { return lval_take(v, i); }
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}
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// Empty expression
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if (v->count == 0) { return v; }
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// Single expression
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if (v->count == 1) { return lval_take(v, 0); }
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// Ensure first element is a symbol otherwise
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lval* f = lval_pop(v, 0);
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if (f->type != LVAL_SYM) {
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printf("The type of f is %d\n", f->type);
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lval_del(f); lval_del(v);
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return lval_err("S-expression does not start with symbol");
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}
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lval* result = builtin_op(v, f->sym);
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lval_del(f);
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return result;
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}
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