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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package operators defines the internal function names of operators.
//
// All operators in the expression language are modelled as function calls.
package operators
// String "names" for CEL operators.
const (
// Symbolic operators.
Conditional = "_?_:_"
LogicalAnd = "_&&_"
LogicalOr = "_||_"
LogicalNot = "!_"
Equals = "_==_"
NotEquals = "_!=_"
Less = "_<_"
LessEquals = "_<=_"
Greater = "_>_"
GreaterEquals = "_>=_"
Add = "_+_"
Subtract = "_-_"
Multiply = "_*_"
Divide = "_/_"
Modulo = "_%_"
Negate = "-_"
Index = "_[_]"
OptIndex = "_[?_]"
OptSelect = "_?._"
// Macros, must have a valid identifier.
Has = "has"
All = "all"
Exists = "exists"
ExistsOne = "exists_one"
Map = "map"
Filter = "filter"
// Named operators, must not have be valid identifiers.
NotStrictlyFalse = "@not_strictly_false"
In = "@in"
// Deprecated: named operators with valid identifiers.
OldNotStrictlyFalse = "__not_strictly_false__"
OldIn = "_in_"
)
var (
operators = map[string]string{
"+": Add,
"/": Divide,
"==": Equals,
">": Greater,
">=": GreaterEquals,
"in": In,
"<": Less,
"<=": LessEquals,
"%": Modulo,
"*": Multiply,
"!=": NotEquals,
"-": Subtract,
}
// operatorMap of the operator symbol which refers to a struct containing the display name,
// if applicable, the operator precedence, and the arity.
//
// If the symbol does not have a display name listed in the map, it is only because it requires
// special casing to render properly as text.
operatorMap = map[string]struct {
displayName string
precedence int
arity int
}{
Conditional: {displayName: "", precedence: 8, arity: 3},
LogicalOr: {displayName: "||", precedence: 7, arity: 2},
LogicalAnd: {displayName: "&&", precedence: 6, arity: 2},
Equals: {displayName: "==", precedence: 5, arity: 2},
Greater: {displayName: ">", precedence: 5, arity: 2},
GreaterEquals: {displayName: ">=", precedence: 5, arity: 2},
In: {displayName: "in", precedence: 5, arity: 2},
Less: {displayName: "<", precedence: 5, arity: 2},
LessEquals: {displayName: "<=", precedence: 5, arity: 2},
NotEquals: {displayName: "!=", precedence: 5, arity: 2},
OldIn: {displayName: "in", precedence: 5, arity: 2},
Add: {displayName: "+", precedence: 4, arity: 2},
Subtract: {displayName: "-", precedence: 4, arity: 2},
Divide: {displayName: "/", precedence: 3, arity: 2},
Modulo: {displayName: "%", precedence: 3, arity: 2},
Multiply: {displayName: "*", precedence: 3, arity: 2},
LogicalNot: {displayName: "!", precedence: 2, arity: 1},
Negate: {displayName: "-", precedence: 2, arity: 1},
Index: {displayName: "", precedence: 1, arity: 2},
OptIndex: {displayName: "", precedence: 1, arity: 2},
OptSelect: {displayName: "", precedence: 1, arity: 2},
}
)
// Find the internal function name for an operator, if the input text is one.
func Find(text string) (string, bool) {
op, found := operators[text]
return op, found
}
// FindReverse returns the unmangled, text representation of the operator.
func FindReverse(symbol string) (string, bool) {
op, found := operatorMap[symbol]
if !found {
return "", false
}
return op.displayName, true
}
// FindReverseBinaryOperator returns the unmangled, text representation of a binary operator.
//
// If the symbol does refer to an operator, but the operator does not have a display name the
// result is false.
func FindReverseBinaryOperator(symbol string) (string, bool) {
op, found := operatorMap[symbol]
if !found || op.arity != 2 {
return "", false
}
if op.displayName == "" {
return "", false
}
return op.displayName, true
}
// Precedence returns the operator precedence, where the higher the number indicates
// higher precedence operations.
func Precedence(symbol string) int {
op, found := operatorMap[symbol]
if !found {
return 0
}
return op.precedence
}
// Arity returns the number of argument the operator takes
// -1 is returned if an undefined symbol is provided
func Arity(symbol string) int {
op, found := operatorMap[symbol]
if !found {
return -1
}
return op.arity
}
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