| // Copyright (c) 2013 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "tools/gn/err.h" |
| #include "tools/gn/functions.h" |
| #include "tools/gn/parse_node_value_adapter.h" |
| #include "tools/gn/parse_tree.h" |
| #include "tools/gn/scope.h" |
| |
| namespace functions { |
| |
| const char kForEach[] = "foreach"; |
| const char kForEach_HelpShort[] = |
| "foreach: Iterate over a list."; |
| const char kForEach_Help[] = |
| "foreach: Iterate over a list.\n" |
| "\n" |
| " foreach(<loop_var>, <list>) {\n" |
| " <loop contents>\n" |
| " }\n" |
| "\n" |
| " Executes the loop contents block over each item in the list,\n" |
| " assigning the loop_var to each item in sequence. The loop_var will be\n" |
| " a copy so assigning to it will not mutate the list.\n" |
| "\n" |
| " The block does not introduce a new scope, so that variable assignments\n" |
| " inside the loop will be visible once the loop terminates.\n" |
| "\n" |
| " The loop variable will temporarily shadow any existing variables with\n" |
| " the same name for the duration of the loop. After the loop terminates\n" |
| " the loop variable will no longer be in scope, and the previous value\n" |
| " (if any) will be restored.\n" |
| "\n" |
| "Example\n" |
| "\n" |
| " mylist = [ \"a\", \"b\", \"c\" ]\n" |
| " foreach(i, mylist) {\n" |
| " print(i)\n" |
| " }\n" |
| "\n" |
| " Prints:\n" |
| " a\n" |
| " b\n" |
| " c\n"; |
| |
| Value RunForEach(Scope* scope, |
| const FunctionCallNode* function, |
| const ListNode* args_list, |
| Err* err) { |
| const auto& args_vector = args_list->contents(); |
| if (args_vector.size() != 2) { |
| *err = Err(function, "Wrong number of arguments to foreach().", |
| "Expecting exactly two."); |
| return Value(); |
| } |
| |
| // Extract the loop variable. |
| const IdentifierNode* identifier = args_vector[0]->AsIdentifier(); |
| if (!identifier) { |
| *err = |
| Err(args_vector[0].get(), "Expected an identifier for the loop var."); |
| return Value(); |
| } |
| base::StringPiece loop_var(identifier->value().value()); |
| |
| // Extract the list to iterate over. |
| ParseNodeValueAdapter list_adapter; |
| if (!list_adapter.InitForType(scope, args_vector[1].get(), Value::LIST, err)) |
| return Value(); |
| const std::vector<Value>& list = list_adapter.get().list_value(); |
| |
| // Block to execute. |
| const BlockNode* block = function->block(); |
| if (!block) { |
| *err = Err(function, "Expected { after foreach."); |
| return Value(); |
| } |
| |
| // If the loop variable was previously defined in this scope, save it so we |
| // can put it back after the loop is done. |
| const Value* old_loop_value_ptr = scope->GetValue(loop_var); |
| Value old_loop_value; |
| if (old_loop_value_ptr) |
| old_loop_value = *old_loop_value_ptr; |
| |
| for (const auto& cur : list) { |
| scope->SetValue(loop_var, cur, function); |
| block->Execute(scope, err); |
| if (err->has_error()) |
| return Value(); |
| } |
| |
| // Put back loop var. |
| if (old_loop_value_ptr) { |
| // Put back old value. Use the copy we made, rather than use the pointer, |
| // which will probably point to the new value now in the scope. |
| scope->SetValue(loop_var, old_loop_value, old_loop_value.origin()); |
| } else { |
| // Loop variable was undefined before loop, delete it. |
| scope->RemoveIdentifier(loop_var); |
| } |
| |
| return Value(); |
| } |
| |
| } // namespace functions |