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/
Expression.scala
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/
Expression.scala
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/**
* Copyright (c) 2002-2013 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.cypher.internal.commands.expressions
import org.neo4j.cypher._
import internal.commands.AstNode
import internal.ExecutionContext
import internal.helpers.TypeSafeMathSupport
import internal.symbols._
abstract class Expression extends (ExecutionContext => Any)
with Typed
with TypeSafe
with AstNode[Expression] {
def rewrite(f: Expression => Expression): Expression
def subExpressions = filter( _ != this)
def containsAggregate = exists(_.isInstanceOf[AggregationExpression])
/*When calculating the type of an expression, the expression should also
make sure to check the types of any downstream expressions*/
protected def calculateType(symbols: SymbolTable): CypherType
def evaluateType(expectedType: CypherType, symbols: SymbolTable): CypherType = {
val t = calculateType(symbols)
if (!expectedType.isAssignableFrom(t) &&
!t.isAssignableFrom(expectedType)) {
throw new CypherTypeException("%s expected to be of type %s but it is of type %s".format(this, expectedType, t))
}
t
}
def throwIfSymbolsMissing(symbols: SymbolTable) {
evaluateType(AnyType(), symbols)
}
override def toString() = getClass.getSimpleName
}
case class CachedExpression(key:String, typ:CypherType) extends Expression {
def apply(ctx: ExecutionContext) = ctx(key)
def rewrite(f: (Expression) => Expression) = f(this)
def children = Seq()
def calculateType(symbols: SymbolTable) = typ
def symbolTableDependencies = Set(key)
override def toString() = "Cached(%s of type %s)".format(key, typ)
}
abstract class Arithmetics(left: Expression, right: Expression)
extends Expression with TypeSafeMathSupport {
def throwTypeError(bVal: Any, aVal: Any): Nothing = {
throw new CypherTypeException("Don't know how to " + this + " `" + bVal + "` with `" + aVal + "`")
}
def apply(ctx: ExecutionContext) = {
val aVal = left(ctx)
val bVal = right(ctx)
(aVal, bVal) match {
case (x: Number, y: Number) => calc(x, y)
case _ => throwTypeError(bVal, aVal)
}
}
def calc(a: Number, b: Number): Any
def calculateType(symbols: SymbolTable): CypherType = {
left.evaluateType(NumberType(), symbols)
right.evaluateType(NumberType(), symbols)
NumberType()
}
def children = Seq(left, right)
}
trait ExpressionWInnerExpression extends Expression {
def inner:Expression
def myType:CypherType
def expectedInnerType:CypherType
def calculateType(symbols: SymbolTable): CypherType = {
inner.evaluateType(expectedInnerType, symbols)
myType
}
}