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Support if x := blah: ...

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This commit is contained in:
Bruce Hill 2024-09-11 01:48:15 -04:00
parent 23209a0aab
commit 989dc3f442
3 changed files with 30 additions and 12 deletions
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32
compile.c
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@ -1196,21 +1196,30 @@ CORD compile_statement(env_t *env, ast_t *ast)
} }
case If: { case If: {
auto if_ = Match(ast, If); auto if_ = Match(ast, If);
type_t *cond_t = get_type(env, if_->condition); ast_t *condition = if_->condition;
CORD code = CORD_EMPTY;
if (condition->tag == Declare) {
env = fresh_scope(env);
code = compile_statement(env, condition);
bind_statement(env, condition);
condition = Match(condition, Declare)->var;
}
type_t *cond_t = get_type(env, condition);
if (cond_t->tag == PointerType) { if (cond_t->tag == PointerType) {
code_err(if_->condition, "This pointer will always be non-null, so it should not be used in a conditional."); code_err(condition, "This pointer will always be non-null, so it should not be used in a conditional.");
} else if (cond_t->tag != BoolType && cond_t->tag != TextType && cond_t->tag != OptionalType) { } else if (cond_t->tag != BoolType && cond_t->tag != TextType && cond_t->tag != OptionalType) {
code_err(if_->condition, "Only boolean values, optional pointers, and text can be used in conditionals (this is a %T)", cond_t); code_err(condition, "Only boolean values, optional pointers, and text can be used in conditionals (this is a %T)", cond_t);
} }
env_t *truthy_scope = env; env_t *truthy_scope = env;
CORD condition; CORD condition_code;
if (cond_t->tag == TextType) { if (cond_t->tag == TextType) {
condition = CORD_all("(", compile(env, if_->condition), ").length"); condition_code = CORD_all("(", compile(env, condition), ").length");
} else if (cond_t->tag == OptionalType) { } else if (cond_t->tag == OptionalType) {
if (if_->condition->tag == Var) { if (condition->tag == Var) {
truthy_scope = fresh_scope(env); truthy_scope = fresh_scope(env);
const char *varname = Match(if_->condition, Var)->name; const char *varname = Match(condition, Var)->name;
binding_t *b = get_binding(env, varname); binding_t *b = get_binding(env, varname);
binding_t *nonnull_b = new(binding_t); binding_t *nonnull_b = new(binding_t);
*nonnull_b = *b; *nonnull_b = *b;
@ -1218,14 +1227,17 @@ CORD compile_statement(env_t *env, ast_t *ast)
nonnull_b->code = compile_optional_into_nonnull(env, b); nonnull_b->code = compile_optional_into_nonnull(env, b);
set_binding(truthy_scope, varname, nonnull_b); set_binding(truthy_scope, varname, nonnull_b);
} }
condition = compile_optional_check(env, if_->condition); condition_code = compile_optional_check(env, condition);
} else { } else {
condition = compile(env, if_->condition); condition_code = compile(env, condition);
} }
CORD code = CORD_all("if (", condition, ")", compile_statement(truthy_scope, if_->body)); code = CORD_all(code, "if (", condition_code, ")", compile_statement(truthy_scope, if_->body));
if (if_->else_body) if (if_->else_body)
code = CORD_all(code, "\nelse ", compile_statement(env, if_->else_body)); code = CORD_all(code, "\nelse ", compile_statement(env, if_->else_body));
if (if_->condition->tag == Declare)
code = CORD_all("{\n", code, "}\n");
return code; return code;
} }
case Block: { case Block: {

5
parse.c
View File

@ -1003,8 +1003,9 @@ PARSER(parse_if) {
if (!match_word(&pos, "if")) if (!match_word(&pos, "if"))
return NULL; return NULL;
ast_t *condition = expect(ctx, start, &pos, parse_expr, ast_t *condition = optional(ctx, &pos, parse_declaration);
"I expected to find a condition for this 'if'"); if (!condition)
condition = expect(ctx, start, &pos, parse_expr, "I expected to find a condition for this 'if'");
ast_t *body = expect(ctx, start, &pos, parse_block, "I expected a body for this 'if' statement"); ast_t *body = expect(ctx, start, &pos, parse_block, "I expected a body for this 'if' statement");

5
test/optionals.tm
View File

@ -121,3 +121,8 @@ func main():
fail("Truthy: $nope") fail("Truthy: $nope")
else: !! Falsey: $nope else: !! Falsey: $nope
if yep := maybe_int(yes):
>> yep
= 123 : Int
else: fail("Unreachable")