65 lines
2.1 KiB
TypeScript
65 lines
2.1 KiB
TypeScript
/**
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* @license
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* Copyright Google Inc. All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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export const ANY_STATE = '*';
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export declare type TransitionMatcherFn = (fromState: any, toState: any) => boolean;
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export function parseTransitionExpr(
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transitionValue: string | TransitionMatcherFn, errors: string[]): TransitionMatcherFn[] {
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const expressions: TransitionMatcherFn[] = [];
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if (typeof transitionValue == 'string') {
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(<string>transitionValue)
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.split(/\s*,\s*/)
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.forEach(str => parseInnerTransitionStr(str, expressions, errors));
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} else {
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expressions.push(<TransitionMatcherFn>transitionValue);
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}
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return expressions;
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}
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function parseInnerTransitionStr(
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eventStr: string, expressions: TransitionMatcherFn[], errors: string[]) {
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if (eventStr[0] == ':') {
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eventStr = parseAnimationAlias(eventStr, errors);
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}
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const match = eventStr.match(/^(\*|[-\w]+)\s*(<?[=-]>)\s*(\*|[-\w]+)$/);
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if (match == null || match.length < 4) {
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errors.push(`The provided transition expression "${eventStr}" is not supported`);
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return expressions;
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}
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const fromState = match[1];
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const separator = match[2];
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const toState = match[3];
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expressions.push(makeLambdaFromStates(fromState, toState));
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const isFullAnyStateExpr = fromState == ANY_STATE && toState == ANY_STATE;
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if (separator[0] == '<' && !isFullAnyStateExpr) {
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expressions.push(makeLambdaFromStates(toState, fromState));
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}
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}
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function parseAnimationAlias(alias: string, errors: string[]): string {
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switch (alias) {
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case ':enter':
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return 'void => *';
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case ':leave':
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return '* => void';
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default:
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errors.push(`The transition alias value "${alias}" is not supported`);
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return '* => *';
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}
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}
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function makeLambdaFromStates(lhs: string, rhs: string): TransitionMatcherFn {
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return (fromState: any, toState: any): boolean => {
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const lhsMatch = lhs == ANY_STATE || lhs == fromState;
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const rhsMatch = rhs == ANY_STATE || rhs == toState;
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return lhsMatch && rhsMatch;
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};
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}
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