41 lines
1.2 KiB
TypeScript
41 lines
1.2 KiB
TypeScript
import {Command, CommandData, ParseContext, StrLVal, wrapString} from "./command.js";
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import {Executable} from "../parse.js";
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import {LexInput} from "../lexer.js";
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import {StrVM} from "../vm.js";
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export type OverData = {
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subject: StrLVal,
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exec: Executable<CommandData>,
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}
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export class Over extends Command<OverData> {
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async attemptParse(context: ParseContext): Promise<OverData> {
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return {
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subject: context.popLVal(),
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exec: await context.popExecutable(),
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}
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}
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getDisplayName(): string {
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return 'over'
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}
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isParseCandidate(token: LexInput): boolean {
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return this.isKeyword(token, 'over')
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}
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async execute(vm: StrVM, data: OverData): Promise<StrVM> {
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return vm.tapInPlace(async parentCtx => {
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const oldValue = parentCtx.resolve(data.subject) || wrapString('')
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const newValue = await vm.runInChild(async (child, childCtx) => {
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await childCtx.replaceSubject(() => oldValue)
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await data.exec.command.execute(child, data.exec.data)
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return childCtx.getSubject()
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})
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parentCtx.inScope(scope =>
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scope.setOrShadowValue(data.subject, newValue))
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})
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}
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}
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