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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 prog * parse_prog(struct allocator * alct, struct token_stream * ts) {
struct prog * p = allocate(alct, sizeof(struct prog));
p->stmts = parse_stmts(alct, ts);
return p;
}
struct stmts * parse_stmts(struct allocator * alct, struct token_stream * ts) {
struct stmts * ss = allocate(alct, sizeof(struct stmts));
ss->stmts = allocate(alct, sizeof(struct stmt *));
ss->stmts[0] = NULL;
int capacity = 0;
int len = 0;
while (peek_token(alct, ts)->type != TK_ENDOFFILE) {
struct stmt * s = 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
if (peek_token(alct, ts)->type == TK_NEWLINE) {
next_token(alct, ts);
} else {
fprintf(stderr, "%d:%d expect newline.\n", peek_token(alct, ts)->line, peek_token(alct, ts)->col);
}
ss->stmts[len] = s;
len++;
}
ss->stmts[len] = NULL;
return ss;
}
struct label * parse_label(struct allocator * alct, struct token_stream * ts) {
struct token * t = next_token(alct, ts);
if (t->type != TK_TAG) {
fprintf(stderr, "%d:%d expect label.\n", t->line, t->col);
exit(-1);
}
struct label * l = allocate(alct, sizeof(struct label *));
l->name = t->sval;
t = next_token(alct, ts);
if (t->type != TK_COLON) {
fprintf(stderr, "%d:%d expect colon.\n", t->line, t->col);
exit(-1);
}
return l;
}
struct stmt * parse_stmt(struct allocator * alct, struct token_stream * ts) {
struct token * t = peek_token(alct, ts);
struct stmt * stmt = allocate(alct, sizeof(struct stmt));
stmt->label = NULL;
stmt->instr = NULL;
if (t->type == TK_TAG) {
stmt->label = parse_label(alct, ts);
if (peek_token(alct, ts)->type == TK_NEWLINE) {
return stmt;
}
t = peek_token(alct, ts);
}
if (t->type == TK_OP) {
stmt->instr = parse_instr(alct, ts);
if (peek_token(alct, ts)->type == TK_NEWLINE) {
return stmt;
}
}
if (t->type == TK_NEWLINE) {
return NULL;
}
fprintf(stderr, "%d:%d expect lable + instruction, lable, or instruction.\n", t->line, t->col);
exit(-1);
}
enum op parse_op(struct allocator * alct, struct token_stream * ts) {
struct token * t = next_token(alct, ts);
enum op op;
if (t->type == TK_OP) {
op = str2op(t->sval);
if (op == OP_END) {
fprintf(stderr, "%d:%d invalid op.\n", t->line, t->col);
exit(-1);
}
} else {
fprintf(stderr, "%d:%d expect op.\n", t->line, t->col);
exit(-1);
}
return op;
}
struct instr * parse_instr(struct allocator * alct, struct token_stream * ts) {
struct token * t = 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 = parse_op(alct, ts);
t = 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;
next_token(alct, ts);
} else if (t->type == TK_TAG) {
i->tag_name = t->sval;
next_token(alct, ts);
}
}
return i;
}
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