9cc/parse.c at master · ebakazu/9cc · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
#include <stdlib.h>
#include <string.h>
#include "9cc.h"

Node *code[100];
LVar *locals;

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;
}

Node *new_node_num(int val) {
    Node *node = calloc(1, sizeof(Node));
    node->kind = ND_NUM;
    node->val = val;
    return node;
}

void program() {
    int i = 0;
    while (!at_eof())
        code[i++] = stmt();
    code[i] = NULL;
}

Node *stmt() {
    Node *node;
    if (consume_return()) {
        node = calloc(1, sizeof(Node));
        node->kind = ND_RETURN;
        node->lhs = expr();
    } else{
        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_NE, node, relational());
        else
            return node;
    }
}

Node *relational() {
    Node *node = add();

    for (;;) {
        if (consume("<"))
            node = new_node(ND_LT, node, add());
        else if (consume("<="))
            node = new_node(ND_LE, node, add());
        else if (consume(">"))
            node = new_node(ND_GT, node, add());
        else if (consume(">="))
            node = new_node(ND_GE, 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();
    }
    if (consume("-")) {
        return new_node(ND_SUB, new_node_num(0), primary());
    }
    return primary();
}

Node *primary() {
    if (consume("(")) {
        Node *node = expr();
        expect(")");
        return node;
    }

    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 {
            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;
        }
        return node;
    }

    return new_node_num(expect_number());
}

LVar *find_lvar(Token *tok) {
    for (LVar *var = locals; var; var = var->next)
        if (var->len == tok->len && !memcmp(tok->str, var->name, var->len))
            return var;
    return NULL;
}