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parse.c
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#include "rincc.h"
Node *code[100];
LVar *locals = NULL;
//新しいノードを生成
Node *new_node(NodeKind kind, Node *lhs, Node *rhs) {
Node *node = calloc(1, sizeof(Node));
node->kind = kind;
node->lhs = lhs;
node->rhs = rhs;
return node;
}
//新しいノードを生成(数値の場合)
Node *new_node_num(int val) {
Node *node = calloc(1, sizeof(Node));
node->kind = ND_NUM;
node->val = val;
return node;
}
LVar *find_Lvar(Token *tok) {
//ポインタがどこを指しているのかがよくわからん
for (LVar *var = locals; var; var = var->next)
{
if (strcmp(var->name, tok->str))
{
return var;
}
}
return NULL;
}
//抽象構文木を生成
Node *program() {
int i = 0;
while (!at_eof())
{
code[i++] = stmt();
}
code[i] = NULL;
return code[0];
}
Node *stmt() {
Node *node = expr();
expect(";");
return node;
}
Node *expr() {
return assign();
}
Node *assign() {
Node *node = equality();
if (consume("="))
{
node = new_node(ND_ASSIGN, node, assign());
}
return node;
}
Node *equality() {
Node *node = relational();
for (;;)
{
if (consume("==")) {
node = new_node(ND_EQ, node, relational());
} else if (consume("!=")) {
node = new_node(ND_NEQ, node, relational());
} else {
return node;
}
}
}
Node *relational() {
Node *node = add();
for (;;)
{
if (consume("=>")) {
node = new_node(ND_EINE, add(), node);
} else if (consume("=<")) {
node = new_node(ND_EINE, node, add());
} else if (consume(">")) {
node = new_node(ND_INE, add(), node);
} else if (consume("<")) {
node = new_node(ND_INE, node, add());
} else {
return node;
}
}
}
Node *add() {
Node *node = mul();
for (;;)
{
if (consume("+")) {
node = new_node(ND_ADD, node, mul());
} else if (consume("-")) {
node = new_node(ND_SUB, node, mul());
} else {
return node;
}
}
}
Node *mul() {
Node *node = unary();
for (;;)
{
if (consume("*")) {
node = new_node(ND_MUL, node, unary());
} else if (consume("/")) {
node = new_node(ND_DIV, node, unary());
} else {
return node;
}
}
}
Node *unary() {
if (consume("+"))
{
return primary();
} else if (consume("-")) {
return new_node(ND_SUB, new_node_num(0), primary());
}
return primary();
}
Node *primary() {
if (consume("(")) {
Node *node = expr();
expect(")");
return node;
}
//ここでconsume_ident()の中のTokenのポインタ*tはポインタtoken”自体の”アドレスを指している。
//なのでtokenの指すアドレスが変わっても*tが指す場所は変わらない。
Token *tok = consume_ident();
if (tok)
{
Node *node = calloc(1, sizeof(Node));
node->kind = ND_LVAR;
LVar *lvar = find_Lvar(tok);
if (lvar)
{
node->offset = lvar->offset;
} else {
if (locals == NULL) //もしlocalsがヌルポインタだったら0クリアしたLVarを代入しておく
{
locals = calloc(1, sizeof(LVar));
}
lvar = calloc(1, sizeof(LVar));
lvar->next = locals;
lvar->name = tok->str;
lvar->len = tok->len;
lvar->offset = locals->offset + 8;
node->offset = lvar->offset;
locals = lvar;
stack_size += 8;
}
return node;
}
return new_node_num(expect_number());
}