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#include "as_parser.h"
#include "as_tokenizer.h"
#include "utils.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// BNF
// ===
//
// <prog> ::= <stmts>
// <stmts> ::= <stmt> newline | <stmt> newline <stmts>
// <stmt> ::= <label> <instr> | <instr> | <label>
// <instr> ::= <op> | <op> arg | <op> tag
// <label> ::= tag ":"
// <op> ::= "add" | "sub" | "mul" | "div" | "mod" | "eq" | ...
struct result parse_prog(struct allocator * alct, struct token_stream * ts) {
struct prog * p = allocate(alct, sizeof(struct prog));
p->stmts = unwrap(parse_stmts(alct, ts));
return ok(p);
}
struct result parse_stmts(struct allocator * alct, struct token_stream * ts) {
struct token *token;
struct stmts * ss = allocate(alct, sizeof(struct stmts));
struct stmt * s;
ss->stmts = allocate(alct, sizeof(struct stmt *));
ss->stmts[0] = NULL;
int capacity = 0;
int len = 0;
while (1) {
token = unwrap(peek_token(alct, ts));
if (token->type == TK_ENDOFFILE) {
break;
}
s = unwrap(parse_stmt(alct, ts));
if (s == NULL) continue;
if (len == capacity) {
size_t new_capacity = capacity * 2 + 1;
void* new_stmts = allocate(alct, sizeof(struct stmt **) * new_capacity);
memcpy(new_stmts, ss->stmts, sizeof(struct stmt **) * capacity);
ss->stmts = new_stmts;
capacity = new_capacity;
}
// expect newline
token = unwrap(peek_token(alct, ts));
if (token->type == TK_NEWLINE) {
unwrap(next_token(alct, ts));
} else {
return err(safe_sprintf(alct, "%d:%d expect newline.\n", token->line, token->col));
}
ss->stmts[len] = s;
len++;
}
ss->stmts[len] = NULL;
return ok(ss);
}
struct result parse_label(struct allocator * alct, struct token_stream * ts) {
struct token * t;
t = unwrap(next_token(alct, ts));
if (t->type != TK_TAG) {
return err(safe_sprintf(alct, "%d:%d expect label.\n", t->line, t->col));
}
struct label * l = allocate(alct, sizeof(struct label *));
l->name = t->sval;
t = unwrap(next_token(alct, ts));
if (t->type != TK_COLON) {
return err(safe_sprintf(alct, "%d:%d expect colon.\n", t->line, t->col));
}
return ok(l);
}
struct result parse_stmt(struct allocator * alct, struct token_stream * ts) {
const char *errmsg;
struct token * token;
token = unwrap(peek_token(alct, ts));
struct stmt * stmt = allocate(alct, sizeof(struct stmt));
stmt->label = NULL;
stmt->instr = NULL;
if (token->type == TK_TAG) {
stmt->label = unwrap(parse_label(alct, ts));
token = unwrap(peek_token(alct, ts));
if (token->type == TK_NEWLINE) {
return ok(stmt);
}
token = unwrap(peek_token(alct, ts));
}
if (token->type == TK_OP) {
stmt->instr = unwrap(parse_instr(alct, ts));
token = unwrap(peek_token(alct, ts));
if (token->type == TK_NEWLINE) {
return ok(stmt);
}
}
if (token->type == TK_NEWLINE) {
return ok(NULL);
}
return err(safe_sprintf(alct, "%d:%d expect lable + instruction, lable, or instruction.\n", token->line, token->col));
}
struct result parse_op(struct allocator * alct, struct token_stream * ts) {
struct token * t;
t = unwrap(next_token(alct, ts));
enum op op;
if (t->type == TK_OP) {
op = str2op(t->sval);
if (op == OP_END) {
return err(safe_sprintf(alct, "%d:%d invalid op.\n", t->line, t->col));
}
} else {
return err(safe_sprintf(alct, "%d:%d expect op.\n", t->line, t->col));
}
return ok((void*)op);
}
struct result parse_instr(struct allocator * alct, struct token_stream * ts) {
struct token * t;
t = unwrap(peek_token(alct, ts));
struct instr * i = allocate(alct, sizeof(struct instr));
i->tag_name = NULL;
i->arg = NULL;
i->op = OP_END;
if (t->type == TK_OP) {
i->op = (enum op)unwrap(parse_op(alct, ts));
t = unwrap(peek_token(alct, ts));
if (t->type == TK_ARG) {
struct arg * a = allocate(alct, sizeof(struct arg));
a->ival = t->ival;
a->fval = t->fval;
i->arg = a;
unwrap(next_token(alct, ts));
} else if (t->type == TK_TAG) {
i->tag_name = t->sval;
unwrap(next_token(alct, ts));
}
}
return ok(i);
}
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