94 lines
2.1 KiB
C
94 lines
2.1 KiB
C
#include "parse.h"
|
|
|
|
#include <assert.h>
|
|
#include <string.h>
|
|
|
|
void parse_init(am_t *am, parse_ctx_t *out)
|
|
{
|
|
out->am = am;
|
|
out->state = PARSE_STATE_INIT;
|
|
out->sp = out->stack + PARSE_MAX_DEPTH - 1;
|
|
}
|
|
|
|
static void push_state(parse_ctx_t *ctx, parse_state_t state)
|
|
{
|
|
assert(ctx->sp >= ctx->stack);
|
|
*ctx->sp-- = state;
|
|
}
|
|
|
|
static parse_state_t pop_state(parse_ctx_t *ctx)
|
|
{
|
|
assert(ctx->sp < ctx->stack + PARSE_MAX_DEPTH - 1);
|
|
return *++ctx->sp;
|
|
}
|
|
|
|
static void append(parse_ctx_t *ctx, expr_t *expr)
|
|
{
|
|
expr_t *list = ctx->am->expr;
|
|
while (!list->is_atom)
|
|
list = list->pair.cdr;
|
|
assert(list->atom.type == ATOM_TYPE_EMPTY_LIST);
|
|
|
|
list->is_atom = false;
|
|
list->pair.car = expr;
|
|
list->pair.cdr = expr_empty_list(ctx->am);
|
|
}
|
|
|
|
parse_state_t parse_proc(parse_ctx_t *ctx, const token_t *token)
|
|
{
|
|
switch (ctx->state) {
|
|
case PARSE_STATE_INIT:
|
|
switch (token->type) {
|
|
case TOKEN_TYPE_INTEGER:
|
|
ctx->am->expr = expr_integer(ctx->am, token->integer);
|
|
ctx->state = PARSE_STATE_DONE;
|
|
break;
|
|
case TOKEN_TYPE_SYMBOL:
|
|
ctx->am->expr = expr_symbol(ctx->am, &token->symbol);
|
|
ctx->state = PARSE_STATE_DONE;
|
|
break;
|
|
case TOKEN_TYPE_OPEN_PAREN:
|
|
push_state(ctx, PARSE_STATE_DONE);
|
|
ctx->am->expr = expr_empty_list(ctx->am);
|
|
ctx->state = PARSE_STATE_LIST;
|
|
break;
|
|
case TOKEN_TYPE_CLOSE_PAREN:
|
|
ctx->state = PARSE_STATE_ERROR;
|
|
break;
|
|
}
|
|
break;
|
|
|
|
case PARSE_STATE_LIST:
|
|
switch (token->type) {
|
|
case TOKEN_TYPE_INTEGER:
|
|
append(ctx, expr_integer(ctx->am, token->integer));
|
|
break;
|
|
case TOKEN_TYPE_SYMBOL:
|
|
append(ctx, expr_symbol(ctx->am, &token->symbol));
|
|
break;
|
|
case TOKEN_TYPE_OPEN_PAREN:
|
|
am_push(ctx->am);
|
|
push_state(ctx, PARSE_STATE_LIST);
|
|
ctx->am->expr = expr_empty_list(ctx->am);
|
|
ctx->state = PARSE_STATE_LIST;
|
|
break;
|
|
case TOKEN_TYPE_CLOSE_PAREN:
|
|
ctx->state = pop_state(ctx);
|
|
if (ctx->state == PARSE_STATE_LIST) {
|
|
expr_t *expr = ctx->am->expr;
|
|
am_pop(ctx->am);
|
|
append(ctx, expr);
|
|
}
|
|
break;
|
|
}
|
|
break;
|
|
|
|
case PARSE_STATE_DONE:
|
|
case PARSE_STATE_ERROR:
|
|
break;
|
|
}
|
|
|
|
assert(ctx->state != PARSE_STATE_INIT);
|
|
return ctx->state;
|
|
}
|