75 lines
1.6 KiB
TypeScript
75 lines
1.6 KiB
TypeScript
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import {
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TokenStream,
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SyntaxKind,
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Syntax,
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SourceFile,
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Decl,
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Statement
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} from "./ast"
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import { Parser, ParseError } from "./parser"
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type Transformer = (tokens: TokenStream) => Syntax;
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export class Expander {
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transformers = new Map<string, Transformer>();
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constructor(public parser: Parser) {
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this.transformers.set('fn', parser.parseFuncDecl.bind(parser))
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this.transformers.set('let', parser.parseVarDecl.bind(parser))
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this.transformers.set('return', parser.parseRetStmt.bind(parser))
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}
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getFullyExpanded(node: Syntax): Syntax {
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if (node.kind === SyntaxKind.SourceFile) {
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const expanded: (Decl | Statement)[] = [];
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for (const element of node.elements) {
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if (element.kind === SyntaxKind.Sentence) {
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const newElement = this.getFullyExpanded(element)
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expanded.push(newElement as Decl | Statement)
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}
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}
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return new SourceFile(expanded, null, node);
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} else if (node.kind === SyntaxKind.Sentence) {
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while (true) {
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console.log('expanding sententce')
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const tokens: TokenStream = node.toStream()
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const t0 = tokens.peek();
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if (t0.kind !== SyntaxKind.Identifier) {
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throw new ParseError(t0, [SyntaxKind.Identifier]);
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}
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if (!this.transformers.has(t0.text)) {
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throw new Error(`the macro '${t0.text}' does not seem to exist`)
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}
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node = this.transformers.get(t0.text)!(tokens)
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if (node.kind !== SyntaxKind.Sentence) {
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break;
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}
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}
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return node
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} else {
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throw new Error(`unrecognised node of kind ${node.kind}`)
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}
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}
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}
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