44 lines
1.1 KiB
TypeScript
44 lines
1.1 KiB
TypeScript
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import { IPrefixParselet } from './prefix'
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import { Token } from '../../tokenizer/token'
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import { Parser } from '../parse'
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import { NameExpression } from '../expressions/name'
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import { ContextSwitchExpression } from '../expressions/contextSwitch'
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export class NameParselet implements IPrefixParselet {
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constructor(public precedence = 0) {}
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parse(parser: Parser, token: Token) {
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const nameExpr = new NameExpression(
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parser.executionEnv,
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token.getText()
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)
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const nextTokens = <const>[parser.lookAhead(0), parser.lookAhead(1)]
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// Context switching operator "->"
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if (
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nextTokens[0].getType() === 'MINUS' &&
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nextTokens[1].getType() === 'GREATER'
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) {
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parser.consume('MINUS')
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parser.consume('GREATER')
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const nameToken = parser.lookAhead(0)
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if (nameToken.getType() !== 'NAME')
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throw new Error(
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`Cannot use context switch operator "->" on ${parser.lookAhead(
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0
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)}`
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)
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parser.consume('NAME')
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return new ContextSwitchExpression(
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nameExpr,
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new NameExpression(parser.executionEnv, nameToken.getText())
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)
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}
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return nameExpr
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}
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}
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