120 lines
3.2 KiB
C
120 lines
3.2 KiB
C
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#include <inttypes.h>
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#include <malloc.h>
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#include <stdio.h>
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#include <string.h>
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struct AST {
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enum AST_type { AST_BINOP, AST_UNOP, AST_LIT } type;
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union {
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struct binop {
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enum binop_type { BIN_PLUS, BIN_MINUS, BIN_MUL, BIN_DIV } type;
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struct AST *left, *right;
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} as_binop;
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struct unop {
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enum unop_type { UN_NEG } type;
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struct AST *operand;
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} as_unop;
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struct literal {
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int64_t value;
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} as_literal;
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};
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};
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/* DSL */
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static struct AST *newnode(struct AST ast) {
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struct AST *const node = malloc(sizeof(struct AST));
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*node = ast;
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return node;
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}
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struct AST _lit(int64_t value) {
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return (struct AST){AST_LIT, .as_literal = {value}};
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}
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struct AST *lit(int64_t value) {
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return newnode(_lit(value));
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}
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struct AST _unop(enum unop_type type, struct AST *operand) {
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return (struct AST){AST_UNOP, .as_unop = {type, operand}};
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}
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struct AST *unop(enum unop_type type, struct AST *operand) {
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return newnode(_unop(type, operand));
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}
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struct AST _binop(enum binop_type type, struct AST *left, struct AST *right) {
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return (struct AST){AST_BINOP, .as_binop = {type, left, right}};
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}
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struct AST *binop(enum binop_type type, struct AST *left, struct AST *right) {
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return newnode(_binop(type, left, right));
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}
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#define DECLARE_BINOP(fun, code) \
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struct AST *fun(struct AST *left, struct AST *right) { \
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return binop(BIN_##code, left, right); \
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}
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DECLARE_BINOP(add, PLUS)
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DECLARE_BINOP(mul, MUL)
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DECLARE_BINOP(sub, MINUS)
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DECLARE_BINOP(div, DIV)
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#undef DECLARE_BINOP
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#define DECLARE_UNOP(fun, code) \
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struct AST *fun(struct AST *operand) { \
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return unop(UN_##code, operand); \
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}
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DECLARE_UNOP(neg, NEG)
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#undef DECLARE_UNOP
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/* printer */
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static const char *BINOPS[] = {
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[BIN_PLUS] = "+", [BIN_MINUS] = "-", [BIN_MUL] = "*", [BIN_DIV] = "/"};
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static const char *UNOPS[] = {[UN_NEG] = "-"};
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typedef void(printer)(FILE *, struct AST *);
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void print(FILE *f, struct AST *ast);
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void print_binop(FILE *f, struct AST *ast) {
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fprintf(f, "(");
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print(f, ast->as_binop.left);
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fprintf(f, ")");
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fprintf(f, "%s", BINOPS[ast->as_binop.type]);
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fprintf(f, "(");
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print(f, ast->as_binop.right);
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fprintf(f, ")");
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}
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void print_unop(FILE *f, struct AST *ast) {
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fprintf(f, "(%s", UNOPS[ast->as_unop.type]);
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print(f, ast->as_unop.operand);
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fprintf(f, ")");
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}
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void print_lit(FILE *f, struct AST *ast) {
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fprintf(f, "%" PRId64, ast->as_literal.value);
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}
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static printer *ast_printers[] = {
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[AST_BINOP] = print_binop, [AST_UNOP] = print_unop, [AST_LIT] = print_lit};
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void print(FILE *f, struct AST *ast) {
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if (ast)
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ast_printers[ast->type](f, ast);
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else
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fprintf(f, "<NULL>");
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}
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int main() {
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struct AST *ast = binop(BIN_PLUS, lit(999), lit(728));;
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print(stdout, ast);
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printf("\n");
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ast = binop(BIN_PLUS, lit(4), binop(BIN_MUL, lit(2), lit(9)));
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print(stdout, ast);
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printf("\n");
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ast = binop(BIN_MUL, binop(BIN_PLUS, lit(3), lit(5)), binop(BIN_DIV, lit(9), lit(7)));
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print(stdout, ast);
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printf("\n");
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return 0;
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}
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