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Added 'else if' support.

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yhirose 2015-05-28 21:35:58 -04:00
parent 0ed897dd01
commit a7c2de1c32
2 changed files with 13 additions and 6 deletions
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15
language/interpreter.cc
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@ -56,12 +56,19 @@ private:
} }
static Value eval_if(const Ast& ast, Env& env) { static Value eval_if(const Ast& ast, Env& env) {
auto cond = eval(*ast.nodes[0], env); const auto& nodes = ast.nodes;
for (auto i = 0u; i < nodes.size(); i += 2) {
if (i + 1 == nodes.size()) {
return eval(*nodes[i], env);
} else {
auto cond = eval(*nodes[i], env);
if (cond.to_bool()) { if (cond.to_bool()) {
return eval(*ast.nodes[1], env); return eval(*nodes[i + 1], env);
} else if (ast.nodes.size() > 2) {
return eval(*ast.nodes[2], env);
} }
}
}
return Value(); return Value();
} }

2
language/parser.cc
View File

@ -11,7 +11,7 @@ static auto g_grammar = R"(
EXPRESSION <- ASSIGNMENT / PRIMARY EXPRESSION <- ASSIGNMENT / PRIMARY
ASSIGNMENT <- IDENTIFIER '=' _ EXPRESSION ASSIGNMENT <- IDENTIFIER '=' _ EXPRESSION
WHILE <- 'while' _ EXPRESSION BLOCK WHILE <- 'while' _ EXPRESSION BLOCK
IF <- 'if' _ EXPRESSION BLOCK ('else' _ BLOCK)? IF <- 'if' _ EXPRESSION BLOCK ('else' _ 'if' _ EXPRESSION BLOCK)* ('else' _ BLOCK)?
FUNCTION <- 'fn' _ PARAMETERS BLOCK FUNCTION <- 'fn' _ PARAMETERS BLOCK
PARAMETERS <- '(' _ IDENTIFIER* ')' _ PARAMETERS <- '(' _ IDENTIFIER* ')' _
FUNCTION_CALL <- IDENTIFIER ARGUMENTS FUNCTION_CALL <- IDENTIFIER ARGUMENTS