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try expression can omit variable assignments

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This commit is contained in:
Andrew Kelley 2017-02-05 18:58:58 -05:00
parent b9c943b066
commit 7749ffd797
3 changed files with 43 additions and 12 deletions
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2
doc/langref.md
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@ -93,7 +93,7 @@ IfExpression = IfVarExpression | IfBoolExpression
IfBoolExpression = "if" "(" Expression ")" Expression option(Else)
TryExpression = "try" "(" ("const" | "var") option("*") Symbol "=" Expression ")" Expression option("else" option("|" Symbol "|") Expression)
TryExpression = "try" "(" option(("const" | "var") option("*") Symbol "=") Expression ")" Expression option("else" option("|" Symbol "|") Expression)
IfVarExpression = "if" "(" ("const" | "var") option("*") Symbol option(":" TypeExpr) "?=" Expression ")" Expression Option(Else)

27
src/parser.cpp
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@ -628,7 +628,7 @@ static AstNode *ast_parse_comptime_expr(ParseContext *pc, size_t *token_index, b
}
/*
TryExpression = "try" "(" ("const" | "var") option("*") Symbol "=" Expression ")" Expression option("else" option("|" Symbol "|") Expression)
TryExpression = "try" "(" option(("const" | "var") option("*") Symbol "=") Expression ")" Expression option("else" option("|" Symbol "|") Expression)
*/
static AstNode *ast_parse_try_expr(ParseContext *pc, size_t *token_index, bool mandatory) {
Token *try_token = &pc->tokens->at(*token_index);
@ -646,27 +646,32 @@ static AstNode *ast_parse_try_expr(ParseContext *pc, size_t *token_index, bool m
ast_eat_token(pc, token_index, TokenIdLParen);
Token *var_token = &pc->tokens->at(*token_index);
bool have_vars;
if (var_token->id == TokenIdKeywordVar) {
node->data.try_expr.var_is_const = false;
*token_index += 1;
have_vars = true;
} else if (var_token->id == TokenIdKeywordConst) {
node->data.try_expr.var_is_const = true;
*token_index += 1;
have_vars = true;
} else {
ast_invalid_token_error(pc, var_token);
have_vars = false;
}
Token *star_token = &pc->tokens->at(*token_index);
if (star_token->id == TokenIdStar) {
node->data.try_expr.var_is_ptr = true;
*token_index += 1;
if (have_vars) {
Token *star_token = &pc->tokens->at(*token_index);
if (star_token->id == TokenIdStar) {
node->data.try_expr.var_is_ptr = true;
*token_index += 1;
}
Token *var_name_tok = ast_eat_token(pc, token_index, TokenIdSymbol);
node->data.try_expr.var_symbol = token_buf(var_name_tok);
ast_eat_token(pc, token_index, TokenIdEq);
}
Token *var_name_tok = ast_eat_token(pc, token_index, TokenIdSymbol);
node->data.try_expr.var_symbol = token_buf(var_name_tok);
ast_eat_token(pc, token_index, TokenIdEq);
node->data.try_expr.target_node = ast_parse_expression(pc, token_index, true);
ast_eat_token(pc, token_index, TokenIdRParen);

26
test/cases/try.zig
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@ -31,3 +31,29 @@ error CrappedOut;
fn returnsTen() -> %i32 {
10
}
fn tryWithoutVars() {
@setFnTest(this);
const result1 = try (failIfTrue(true)) {
1
} else {
i32(2)
};
assert(result1 == 2);
const result2 = try (failIfTrue(false)) {
1
} else {
i32(2)
};
assert(result2 == 1);
}
fn failIfTrue(ok: bool) -> %void {
if (ok) {
return error.ItBroke;
} else {
return;
}
}