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"use strict" ;
/ * *
* @ license
* Copyright 2017 Palantir Technologies , Inc .
*
* 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 .
* /
Object . defineProperty ( exports , "__esModule" , { value : true } ) ;
var tslib _1 = require ( "tslib" ) ;
var tsutils _1 = require ( "tsutils" ) ;
var ts = require ( "typescript" ) ;
var Lint = require ( "../index" ) ;
var utils _1 = require ( "../language/utils" ) ;
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var Rule = /** @class */ ( function ( _super ) {
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tslib _1 . _ _extends ( Rule , _super ) ;
function Rule ( ) {
return _super !== null && _super . apply ( this , arguments ) || this ;
}
Rule . prototype . apply = function ( sourceFile ) {
return this . applyWithFunction ( sourceFile , walk ) ;
} ;
/* tslint:disable:object-literal-sort-keys */
Rule . metadata = {
ruleName : "binary-expression-operand-order" ,
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description : Lint . Utils . dedent ( templateObject _1 || ( templateObject _1 = tslib _1 . _ _makeTemplateObject ( [ "\n In a binary expression, a literal should always be on the right-hand side if possible.\n For example, prefer 'x + 1' over '1 + x'." ] , [ "\n In a binary expression, a literal should always be on the right-hand side if possible.\n For example, prefer 'x + 1' over '1 + x'." ] ) ) ) ,
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optionsDescription : "Not configurable." ,
options : null ,
optionExamples : [ true ] ,
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rationale : Lint . Utils . dedent ( templateObject _2 || ( templateObject _2 = tslib _1 . _ _makeTemplateObject ( [ "\n Expressions like `1 + x` are sometimes referred to as \"Yoda\" expressions because they read\n opposite to how we would normally speak the expression.\n\n Sticking to a consistent grammar for conditions helps keep code readable and understandable.\n " ] , [ "\n Expressions like \\`1 + x\\` are sometimes referred to as \"Yoda\" expressions because they read\n opposite to how we would normally speak the expression.\n\n Sticking to a consistent grammar for conditions helps keep code readable and understandable.\n " ] ) ) ) ,
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type : "style" ,
typescriptOnly : false ,
} ;
/* tslint:enable:object-literal-sort-keys */
Rule . FAILURE _STRING = "Literal expression should be on the right-hand side of a binary expression." ;
return Rule ;
} ( Lint . Rules . AbstractRule ) ) ;
exports . Rule = Rule ;
function walk ( ctx ) {
ts . forEachChild ( ctx . sourceFile , function cb ( node ) {
if ( tsutils _1 . isBinaryExpression ( node ) && isLiteral ( node . left ) && ! isLiteral ( node . right ) && ! isAllowedOrderedOperator ( node ) ) {
ctx . addFailureAtNode ( node , Rule . FAILURE _STRING ) ;
}
ts . forEachChild ( node , cb ) ;
} ) ;
}
/** Allows certain inherently ordered operators that can't easily be written with the literal on the right. */
function isAllowedOrderedOperator ( node ) {
switch ( node . operatorToken . kind ) {
case ts . SyntaxKind . PlusToken :
// Allow `"foo" + x` but not `1 + x`.
return node . left . kind === ts . SyntaxKind . StringLiteral ;
case ts . SyntaxKind . MinusToken :
case ts . SyntaxKind . SlashToken :
case ts . SyntaxKind . PercentToken :
case ts . SyntaxKind . LessThanLessThanToken :
case ts . SyntaxKind . GreaterThanGreaterThanToken :
case ts . SyntaxKind . GreaterThanGreaterThanGreaterThanToken :
case ts . SyntaxKind . AsteriskAsteriskToken :
case ts . SyntaxKind . InKeyword :
case ts . SyntaxKind . CommaToken :
return true ;
default :
return false ;
}
}
function isLiteral ( node ) {
switch ( node . kind ) {
case ts . SyntaxKind . StringLiteral :
case ts . SyntaxKind . NumericLiteral :
case ts . SyntaxKind . TrueKeyword :
case ts . SyntaxKind . FalseKeyword :
case ts . SyntaxKind . NullKeyword :
return true ;
case ts . SyntaxKind . Identifier :
return node . originalKeywordKind === ts . SyntaxKind . UndefinedKeyword ;
case ts . SyntaxKind . PrefixUnaryExpression :
return utils _1 . isNegativeNumberLiteral ( node ) ;
case ts . SyntaxKind . ParenthesizedExpression :
return isLiteral ( node . expression ) ;
default :
return false ;
}
}
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var templateObject _1 , templateObject _2 ;