tools/gn/operators.cc

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This source file includes following definitions.
AppendFilteredSourcesToValue
RemoveMatchesFromList
ExecuteEquals
ValuePlusEquals
ExecutePlusEquals
ValueMinusEquals
ExecuteMinusEquals
ExecutePlus
ExecuteMinus
ExecuteEqualsEquals
ExecuteNotEquals
FillNeedsTwoIntegersError
ExecuteLessEquals
ExecuteGreaterEquals
ExecuteGreater
ExecuteLess
ExecuteOr
ExecuteAnd
IsUnaryOperator
IsBinaryOperator
IsFunctionCallArgBeginScoper
IsFunctionCallArgEndScoper
IsScopeBeginScoper
IsScopeEndScoper
ExecuteUnaryOperator
ExecuteBinaryOperator
// 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/operators.h"

#include "base/strings/string_number_conversions.h"
#include "tools/gn/err.h"
#include "tools/gn/parse_tree.h"
#include "tools/gn/scope.h"
#include "tools/gn/token.h"
#include "tools/gn/value.h"

namespace {

const char kSourcesName[] = "sources";

// Applies the sources assignment filter from the given scope to each element
// of source (can be a list or a string), appending it to dest if it doesn't
// match.
void AppendFilteredSourcesToValue(const Scope* scope,
                                  const Value& source,
                                  Value* dest) {
  const PatternList* filter = scope->GetSourcesAssignmentFilter();

  if (source.type() == Value::STRING) {
    if (!filter || filter->is_empty() ||
        !filter->MatchesValue(source))
      dest->list_value().push_back(source);
    return;
  }
  if (source.type() != Value::LIST) {
    // Any non-list and non-string being added to a list can just get appended,
    // we're not going to filter it.
    dest->list_value().push_back(source);
    return;
  }

  const std::vector<Value>& source_list = source.list_value();
  if (!filter || filter->is_empty()) {
    // No filter, append everything.
    for (size_t i = 0; i < source_list.size(); i++)
      dest->list_value().push_back(source_list[i]);
    return;
  }

  // Note: don't reserve() the dest vector here since that actually hurts
  // the allocation pattern when the build script is doing multiple small
  // additions.
  for (size_t i = 0; i < source_list.size(); i++) {
    if (!filter->MatchesValue(source_list[i]))
      dest->list_value().push_back(source_list[i]);
  }
}

void RemoveMatchesFromList(const BinaryOpNode* op_node,
                           Value* list,
                           const Value& to_remove,
                           Err* err) {
  std::vector<Value>& v = list->list_value();
  switch (to_remove.type()) {
    case Value::BOOLEAN:
    case Value::INTEGER:  // Filter out the individual int/string.
    case Value::STRING: {
      bool found_match = false;
      for (size_t i = 0; i < v.size(); /* nothing */) {
        if (v[i] == to_remove) {
          found_match = true;
          v.erase(v.begin() + i);
        } else {
          i++;
        }
      }
      if (!found_match) {
        *err = Err(to_remove.origin()->GetRange(), "Item not found",
            "You were trying to remove " + to_remove.ToString(true) +
            "\nfrom the list but it wasn't there.");
      }
      break;
    }

    case Value::LIST:  // Filter out each individual thing.
      for (size_t i = 0; i < to_remove.list_value().size(); i++) {
        // TODO(brettw) if the nested item is a list, we may want to search
        // for the literal list rather than remote the items in it.
        RemoveMatchesFromList(op_node, list, to_remove.list_value()[i], err);
        if (err->has_error())
          return;
      }
      break;

    default:
      break;
  }
}

// Assignment -----------------------------------------------------------------

// We return a null value from this rather than the result of doing the append.
// See ValuePlusEquals for rationale.
Value ExecuteEquals(Scope* scope,
                    const BinaryOpNode* op_node,
                    const Token& left,
                    const Value& right,
                    Err* err) {
  const Value* old_value = scope->GetValue(left.value(), false);
  if (old_value) {
    // Throw an error when overwriting a nonempty list with another nonempty
    // list item. This is to detect the case where you write
    //   defines = ["FOO"]
    // and you overwrote inherited ones, when instead you mean to append:
    //   defines += ["FOO"]
    if (old_value->type() == Value::LIST &&
        !old_value->list_value().empty() &&
        right.type() == Value::LIST &&
        !right.list_value().empty()) {
      *err = Err(op_node->left()->GetRange(), "Replacing nonempty list.",
          std::string("This overwrites a previously-defined nonempty list ") +
          "(length " +
          base::IntToString(static_cast<int>(old_value->list_value().size()))
          + ").");
      err->AppendSubErr(Err(*old_value, "for previous definition",
          "with another one (length " +
          base::IntToString(static_cast<int>(right.list_value().size())) +
          "). Did you mean " +
          "\"+=\" to append instead? If you\nreally want to do this, do\n  " +
          left.value().as_string() + " = []\nbefore reassigning."));
      return Value();
    }
  }
  if (err->has_error())
    return Value();

  if (right.type() == Value::LIST && left.value() == kSourcesName) {
    // Assigning to sources, filter the list. Here we do the filtering and
    // copying in one step to save an extra list copy (the lists may be
    // long).
    Value* set_value = scope->SetValue(left.value(),
                                       Value(op_node, Value::LIST), op_node);
    set_value->list_value().reserve(right.list_value().size());
    AppendFilteredSourcesToValue(scope, right, set_value);
  } else {
    // Normal value set, just copy it.
    scope->SetValue(left.value(), right, op_node->right());
  }
  return Value();
}

// allow_type_conversion indicates if we're allowed to change the type of the
// left value. This is set to true when doing +, and false when doing +=.
//
// Note that we return Value() from here, which is different than C++. This
// means you can't do clever things like foo = [ bar += baz ] to simultaneously
// append to and use a value. This is basically never needed in out build
// scripts and is just as likely an error as the intended behavior, and it also
// involves a copy of the value when it's returned. Many times we're appending
// to large lists, and copying the value to discard it for the next statement
// is very wasteful.
void ValuePlusEquals(const Scope* scope,
                     const BinaryOpNode* op_node,
                     const Token& left_token,
                     Value* left,
                     const Value& right,
                     bool allow_type_conversion,
                     Err* err) {
  switch (left->type()) {
    // Left-hand-side int.
    case Value::INTEGER:
      switch (right.type()) {
        case Value::INTEGER:  // int + int -> addition.
          left->int_value() += right.int_value();
          return;

        case Value::STRING:  // int + string -> string concat.
          if (allow_type_conversion) {
            *left = Value(op_node,
                base::Int64ToString(left->int_value()) + right.string_value());
            return;
          }
          break;

        default:
          break;
      }
      break;

    // Left-hand-side string.
    case Value::STRING:
      switch (right.type()) {
        case Value::INTEGER:  // string + int -> string concat.
          left->string_value().append(base::Int64ToString(right.int_value()));
          return;

        case Value::STRING:  // string + string -> string contat.
          left->string_value().append(right.string_value());
          return;

        default:
          break;
      }
      break;

    // Left-hand-side list.
    case Value::LIST:
      switch (right.type()) {
        case Value::LIST:  // list + list -> list concat.
          if (left_token.value() == kSourcesName) {
            // Filter additions through the assignment filter.
            AppendFilteredSourcesToValue(scope, right, left);
          } else {
            // Normal list concat.
            for (size_t i = 0; i < right.list_value().size(); i++)
              left->list_value().push_back(right.list_value()[i]);
          }
          return;

        default:
          *err = Err(op_node->op(), "Incompatible types to add.",
              "To append a single item to a list do \"foo += [ bar ]\".");
          return;
      }

    default:
      break;
  }

  *err = Err(op_node->op(), "Incompatible types to add.",
      std::string("I see a ") + Value::DescribeType(left->type()) + " and a " +
      Value::DescribeType(right.type()) + ".");
}

Value ExecutePlusEquals(Scope* scope,
                        const BinaryOpNode* op_node,
                        const Token& left,
                        const Value& right,
                        Err* err) {
  // We modify in-place rather than doing read-modify-write to avoid
  // copying large lists.
  Value* left_value =
      scope->GetValueForcedToCurrentScope(left.value(), op_node);
  if (!left_value) {
    *err = Err(left, "Undefined variable for +=.",
        "I don't have something with this name in scope now.");
    return Value();
  }
  ValuePlusEquals(scope, op_node, left, left_value, right, false, err);
  left_value->set_origin(op_node);
  scope->MarkUnused(left.value());
  return Value();
}

// We return a null value from this rather than the result of doing the append.
// See ValuePlusEquals for rationale.
void ValueMinusEquals(const BinaryOpNode* op_node,
                      Value* left,
                      const Value& right,
                      bool allow_type_conversion,
                      Err* err) {
  switch (left->type()) {
    // Left-hand-side int.
    case Value::INTEGER:
      switch (right.type()) {
        case Value::INTEGER:  // int - int -> subtraction.
          left->int_value() -= right.int_value();
          return;

        default:
          break;
      }
      break;

    // Left-hand-side string.
    case Value::STRING:
      break;  // All are errors.

    // Left-hand-side list.
    case Value::LIST:
      if (right.type() != Value::LIST) {
        *err = Err(op_node->op(), "Incompatible types to subtract.",
            "To remove a single item from a list do \"foo -= [ bar ]\".");
      } else {
        RemoveMatchesFromList(op_node, left, right, err);
      }
      return;

    default:
      break;
  }

  *err = Err(op_node->op(), "Incompatible types to subtract.",
      std::string("I see a ") + Value::DescribeType(left->type()) + " and a " +
      Value::DescribeType(right.type()) + ".");
}

Value ExecuteMinusEquals(Scope* scope,
                         const BinaryOpNode* op_node,
                         const Token& left,
                         const Value& right,
                         Err* err) {
  Value* left_value =
      scope->GetValueForcedToCurrentScope(left.value(), op_node);
  if (!left_value) {
    *err = Err(left, "Undefined variable for -=.",
        "I don't have something with this name in scope now.");
    return Value();
  }
  ValueMinusEquals(op_node, left_value, right, false, err);
  left_value->set_origin(op_node);
  scope->MarkUnused(left.value());
  return Value();
}

// Plus/Minus -----------------------------------------------------------------

Value ExecutePlus(Scope* scope,
                  const BinaryOpNode* op_node,
                  const Value& left,
                  const Value& right,
                  Err* err) {
  Value ret = left;
  ValuePlusEquals(scope, op_node, Token(), &ret, right, true, err);
  ret.set_origin(op_node);
  return ret;
}

Value ExecuteMinus(Scope* scope,
                   const BinaryOpNode* op_node,
                   const Value& left,
                   const Value& right,
                   Err* err) {
  Value ret = left;
  ValueMinusEquals(op_node, &ret, right, true, err);
  ret.set_origin(op_node);
  return ret;
}

// Comparison -----------------------------------------------------------------

Value ExecuteEqualsEquals(Scope* scope,
                          const BinaryOpNode* op_node,
                          const Value& left,
                          const Value& right,
                          Err* err) {
  if (left == right)
    return Value(op_node, true);
  return Value(op_node, false);
}

Value ExecuteNotEquals(Scope* scope,
                       const BinaryOpNode* op_node,
                       const Value& left,
                       const Value& right,
                       Err* err) {
  // Evaluate in terms of ==.
  Value result = ExecuteEqualsEquals(scope, op_node, left, right, err);
  result.boolean_value() = !result.boolean_value();
  return result;
}

Value FillNeedsTwoIntegersError(const BinaryOpNode* op_node,
                                const Value& left,
                                const Value& right,
                                Err* err) {
  *err = Err(op_node, "Comparison requires two integers.",
             "This operator can only compare two integers.");
  err->AppendRange(left.origin()->GetRange());
  err->AppendRange(right.origin()->GetRange());
  return Value();
}

Value ExecuteLessEquals(Scope* scope,
                        const BinaryOpNode* op_node,
                        const Value& left,
                        const Value& right,
                        Err* err) {
  if (left.type() != Value::INTEGER || right.type() != Value::INTEGER)
    return FillNeedsTwoIntegersError(op_node, left, right, err);
  return Value(op_node, left.int_value() <= right.int_value());
}

Value ExecuteGreaterEquals(Scope* scope,
                           const BinaryOpNode* op_node,
                           const Value& left,
                           const Value& right,
                           Err* err) {
  if (left.type() != Value::INTEGER || right.type() != Value::INTEGER)
    return FillNeedsTwoIntegersError(op_node, left, right, err);
  return Value(op_node, left.int_value() >= right.int_value());
}

Value ExecuteGreater(Scope* scope,
                     const BinaryOpNode* op_node,
                     const Value& left,
                     const Value& right,
                     Err* err) {
  if (left.type() != Value::INTEGER || right.type() != Value::INTEGER)
    return FillNeedsTwoIntegersError(op_node, left, right, err);
  return Value(op_node, left.int_value() > right.int_value());
}

Value ExecuteLess(Scope* scope,
                  const BinaryOpNode* op_node,
                  const Value& left,
                  const Value& right,
                  Err* err) {
  if (left.type() != Value::INTEGER || right.type() != Value::INTEGER)
    return FillNeedsTwoIntegersError(op_node, left, right, err);
  return Value(op_node, left.int_value() < right.int_value());
}

// Binary ----------------------------------------------------------------------

Value ExecuteOr(Scope* scope,
                const BinaryOpNode* op_node,
                const Value& left,
                const Value& right,
                Err* err) {
  if (left.type() != Value::BOOLEAN) {
    *err = Err(left, "Left side of || operator is not a boolean.");
    err->AppendRange(op_node->GetRange());
  } else if (right.type() != Value::BOOLEAN) {
    *err = Err(right, "Right side of || operator is not a boolean.");
    err->AppendRange(op_node->GetRange());
  }
  return Value(op_node, left.boolean_value() || right.boolean_value());
}

Value ExecuteAnd(Scope* scope,
                 const BinaryOpNode* op_node,
                 const Value& left,
                 const Value& right,
                 Err* err) {
  if (left.type() != Value::BOOLEAN) {
    *err = Err(left, "Left side of && operator is not a boolean.");
    err->AppendRange(op_node->GetRange());
  } else if (right.type() != Value::BOOLEAN) {
    *err = Err(right, "Right side of && operator is not a boolean.");
    err->AppendRange(op_node->GetRange());
  }
  return Value(op_node, left.boolean_value() && right.boolean_value());
}

}  // namespace

// ----------------------------------------------------------------------------

bool IsUnaryOperator(const Token& token) {
  return token.type() == Token::BANG;
}

bool IsBinaryOperator(const Token& token) {
  return token.type() == Token::EQUAL ||
         token.type() == Token::PLUS ||
         token.type() == Token::MINUS ||
         token.type() == Token::PLUS_EQUALS ||
         token.type() == Token::MINUS_EQUALS ||
         token.type() == Token::EQUAL_EQUAL ||
         token.type() == Token::NOT_EQUAL ||
         token.type() == Token::LESS_EQUAL ||
         token.type() == Token::GREATER_EQUAL ||
         token.type() == Token::LESS_THAN ||
         token.type() == Token::GREATER_THAN ||
         token.type() == Token::BOOLEAN_AND ||
         token.type() == Token::BOOLEAN_OR;
}

bool IsFunctionCallArgBeginScoper(const Token& token) {
  return token.type() == Token::LEFT_PAREN;
}

bool IsFunctionCallArgEndScoper(const Token& token) {
  return token.type() == Token::RIGHT_PAREN;
}

bool IsScopeBeginScoper(const Token& token) {
  return token.type() == Token::LEFT_BRACE;
}

bool IsScopeEndScoper(const Token& token) {
  return token.type() == Token::RIGHT_BRACE;
}

Value ExecuteUnaryOperator(Scope* scope,
                           const UnaryOpNode* op_node,
                           const Value& expr,
                           Err* err) {
  DCHECK(op_node->op().type() == Token::BANG);

  if (expr.type() != Value::BOOLEAN) {
    *err = Err(expr, "Operand of ! operator is not a boolean.");
    err->AppendRange(op_node->GetRange());
    return Value();
  }
  // TODO(scottmg): Why no unary minus?
  return Value(op_node, !expr.boolean_value());
}

Value ExecuteBinaryOperator(Scope* scope,
                            const BinaryOpNode* op_node,
                            const ParseNode* left,
                            const ParseNode* right,
                            Err* err) {
  const Token& op = op_node->op();

  // First handle the ones that take an lvalue.
  if (op.type() == Token::EQUAL ||
      op.type() == Token::PLUS_EQUALS ||
      op.type() == Token::MINUS_EQUALS) {
    const IdentifierNode* left_id = left->AsIdentifier();
    if (!left_id) {
      *err = Err(op, "Operator requires a lvalue.",
                 "This thing on the left is not an identifier.");
      err->AppendRange(left->GetRange());
      return Value();
    }
    const Token& dest = left_id->value();

    Value right_value = right->Execute(scope, err);
    if (err->has_error())
      return Value();
    if (right_value.type() == Value::NONE) {
      *err = Err(op, "Operator requires a rvalue.",
                 "This thing on the right does not evaluate to a value.");
      err->AppendRange(right->GetRange());
      return Value();
    }

    if (op.type() == Token::EQUAL)
      return ExecuteEquals(scope, op_node, dest, right_value, err);
    if (op.type() == Token::PLUS_EQUALS)
      return ExecutePlusEquals(scope, op_node, dest, right_value, err);
    if (op.type() == Token::MINUS_EQUALS)
      return ExecuteMinusEquals(scope, op_node, dest, right_value, err);
    NOTREACHED();
    return Value();
  }

  // Left value.
  Value left_value = left->Execute(scope, err);
  if (err->has_error())
    return Value();
  if (left_value.type() == Value::NONE) {
    *err = Err(op, "Operator requires a value.",
               "This thing on the left does not evaluate to a value.");
    err->AppendRange(left->GetRange());
    return Value();
  }

  // Right value. Note: don't move this above to share code with the lvalue
  // version since in this case we want to execute the left side first.
  Value right_value = right->Execute(scope, err);
  if (err->has_error())
    return Value();
  if (right_value.type() == Value::NONE) {
    *err = Err(op, "Operator requires a value.",
               "This thing on the right does not evaluate to a value.");
    err->AppendRange(right->GetRange());
    return Value();
  }

  // +, -.
  if (op.type() == Token::MINUS)
    return ExecuteMinus(scope, op_node, left_value, right_value, err);
  if (op.type() == Token::PLUS)
    return ExecutePlus(scope, op_node, left_value, right_value, err);

  // Comparisons.
  if (op.type() == Token::EQUAL_EQUAL)
    return ExecuteEqualsEquals(scope, op_node, left_value, right_value, err);
  if (op.type() == Token::NOT_EQUAL)
    return ExecuteNotEquals(scope, op_node, left_value, right_value, err);
  if (op.type() == Token::GREATER_EQUAL)
    return ExecuteGreaterEquals(scope, op_node, left_value, right_value, err);
  if (op.type() == Token::LESS_EQUAL)
    return ExecuteLessEquals(scope, op_node, left_value, right_value, err);
  if (op.type() == Token::GREATER_THAN)
    return ExecuteGreater(scope, op_node, left_value, right_value, err);
  if (op.type() == Token::LESS_THAN)
    return ExecuteLess(scope, op_node, left_value, right_value, err);

  // ||, &&.
  if (op.type() == Token::BOOLEAN_OR)
    return ExecuteOr(scope, op_node, left_value, right_value, err);
  if (op.type() == Token::BOOLEAN_AND)
    return ExecuteAnd(scope, op_node, left_value, right_value, err);

  return Value();
}
/* [<][>][^][v][top][bottom][index][help] */
root/tools/gn/operators.cc

DEFINITIONS
