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615 lines
15 KiB
TypeScript
615 lines
15 KiB
TypeScript
// Loaded from https://deno.land/x/graphql_deno@v15.0.0/lib/language/lexer.js
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import { syntaxError } from '../error/syntaxError.js';
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import { Token } from './ast.js';
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import { dedentBlockStringValue } from './blockString.js';
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import { TokenKind } from './tokenKind.js';
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/**
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* Given a Source object, creates a Lexer for that source.
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* A Lexer is a stateful stream generator in that every time
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* it is advanced, it returns the next token in the Source. Assuming the
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* source lexes, the final Token emitted by the lexer will be of kind
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* EOF, after which the lexer will repeatedly return the same EOF token
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* whenever called.
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*/
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export class Lexer {
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/**
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* The previously focused non-ignored token.
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*/
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/**
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* The currently focused non-ignored token.
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*/
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/**
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* The (1-indexed) line containing the current token.
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*/
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/**
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* The character offset at which the current line begins.
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*/
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constructor(source) {
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const startOfFileToken = new Token(TokenKind.SOF, 0, 0, 0, 0, null);
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this.source = source;
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this.lastToken = startOfFileToken;
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this.token = startOfFileToken;
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this.line = 1;
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this.lineStart = 0;
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}
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/**
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* Advances the token stream to the next non-ignored token.
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*/
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advance() {
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this.lastToken = this.token;
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const token = this.token = this.lookahead();
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return token;
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}
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/**
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* Looks ahead and returns the next non-ignored token, but does not change
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* the state of Lexer.
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*/
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lookahead() {
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let token = this.token;
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if (token.kind !== TokenKind.EOF) {
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do {
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// Note: next is only mutable during parsing, so we cast to allow this.
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token = token.next ?? (token.next = readToken(this, token));
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} while (token.kind === TokenKind.COMMENT);
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}
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return token;
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}
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}
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/**
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* @internal
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*/
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export function isPunctuatorTokenKind(kind) {
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return kind === TokenKind.BANG || kind === TokenKind.DOLLAR || kind === TokenKind.AMP || kind === TokenKind.PAREN_L || kind === TokenKind.PAREN_R || kind === TokenKind.SPREAD || kind === TokenKind.COLON || kind === TokenKind.EQUALS || kind === TokenKind.AT || kind === TokenKind.BRACKET_L || kind === TokenKind.BRACKET_R || kind === TokenKind.BRACE_L || kind === TokenKind.PIPE || kind === TokenKind.BRACE_R;
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}
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function printCharCode(code) {
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return (// NaN/undefined represents access beyond the end of the file.
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isNaN(code) ? TokenKind.EOF : // Trust JSON for ASCII.
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code < 0x007f ? JSON.stringify(String.fromCharCode(code)) : // Otherwise print the escaped form.
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`"\\u${('00' + code.toString(16).toUpperCase()).slice(-4)}"`
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);
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}
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/**
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* Gets the next token from the source starting at the given position.
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*
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* This skips over whitespace until it finds the next lexable token, then lexes
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* punctuators immediately or calls the appropriate helper function for more
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* complicated tokens.
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*/
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function readToken(lexer, prev) {
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const source = lexer.source;
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const body = source.body;
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const bodyLength = body.length;
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const pos = positionAfterWhitespace(body, prev.end, lexer);
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const line = lexer.line;
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const col = 1 + pos - lexer.lineStart;
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if (pos >= bodyLength) {
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return new Token(TokenKind.EOF, bodyLength, bodyLength, line, col, prev);
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}
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const code = body.charCodeAt(pos); // SourceCharacter
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switch (code) {
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// !
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case 33:
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return new Token(TokenKind.BANG, pos, pos + 1, line, col, prev);
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// #
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case 35:
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return readComment(source, pos, line, col, prev);
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// $
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case 36:
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return new Token(TokenKind.DOLLAR, pos, pos + 1, line, col, prev);
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// &
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case 38:
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return new Token(TokenKind.AMP, pos, pos + 1, line, col, prev);
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// (
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case 40:
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return new Token(TokenKind.PAREN_L, pos, pos + 1, line, col, prev);
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// )
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case 41:
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return new Token(TokenKind.PAREN_R, pos, pos + 1, line, col, prev);
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// .
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case 46:
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if (body.charCodeAt(pos + 1) === 46 && body.charCodeAt(pos + 2) === 46) {
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return new Token(TokenKind.SPREAD, pos, pos + 3, line, col, prev);
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}
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break;
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// :
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case 58:
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return new Token(TokenKind.COLON, pos, pos + 1, line, col, prev);
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// =
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case 61:
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return new Token(TokenKind.EQUALS, pos, pos + 1, line, col, prev);
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// @
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case 64:
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return new Token(TokenKind.AT, pos, pos + 1, line, col, prev);
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// [
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case 91:
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return new Token(TokenKind.BRACKET_L, pos, pos + 1, line, col, prev);
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// ]
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case 93:
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return new Token(TokenKind.BRACKET_R, pos, pos + 1, line, col, prev);
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// {
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case 123:
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return new Token(TokenKind.BRACE_L, pos, pos + 1, line, col, prev);
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// |
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case 124:
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return new Token(TokenKind.PIPE, pos, pos + 1, line, col, prev);
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// }
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case 125:
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return new Token(TokenKind.BRACE_R, pos, pos + 1, line, col, prev);
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// A-Z _ a-z
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case 65:
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case 66:
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case 67:
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case 68:
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case 69:
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case 70:
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case 71:
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case 72:
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case 73:
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case 74:
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case 75:
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case 76:
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case 77:
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case 78:
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case 79:
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case 80:
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case 81:
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case 82:
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case 83:
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case 84:
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case 85:
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case 86:
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case 87:
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case 88:
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case 89:
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case 90:
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case 95:
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case 97:
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case 98:
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case 99:
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case 100:
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case 101:
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case 102:
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case 103:
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case 104:
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case 105:
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case 106:
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case 107:
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case 108:
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case 109:
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case 110:
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case 111:
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case 112:
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case 113:
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case 114:
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case 115:
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case 116:
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case 117:
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case 118:
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case 119:
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case 120:
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case 121:
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case 122:
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return readName(source, pos, line, col, prev);
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// - 0-9
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case 45:
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case 48:
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case 49:
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case 50:
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case 51:
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case 52:
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case 53:
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case 54:
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case 55:
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case 56:
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case 57:
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return readNumber(source, pos, code, line, col, prev);
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// "
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case 34:
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if (body.charCodeAt(pos + 1) === 34 && body.charCodeAt(pos + 2) === 34) {
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return readBlockString(source, pos, line, col, prev, lexer);
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}
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return readString(source, pos, line, col, prev);
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}
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throw syntaxError(source, pos, unexpectedCharacterMessage(code));
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}
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/**
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* Report a message that an unexpected character was encountered.
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*/
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function unexpectedCharacterMessage(code) {
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if (code < 0x0020 && code !== 0x0009 && code !== 0x000a && code !== 0x000d) {
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return `Cannot contain the invalid character ${printCharCode(code)}.`;
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}
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if (code === 39) {
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// '
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return 'Unexpected single quote character (\'), did you mean to use a double quote (")?';
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}
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return `Cannot parse the unexpected character ${printCharCode(code)}.`;
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}
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/**
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* Reads from body starting at startPosition until it finds a non-whitespace
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* character, then returns the position of that character for lexing.
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*/
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function positionAfterWhitespace(body, startPosition, lexer) {
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const bodyLength = body.length;
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let position = startPosition;
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while (position < bodyLength) {
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const code = body.charCodeAt(position); // tab | space | comma | BOM
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if (code === 9 || code === 32 || code === 44 || code === 0xfeff) {
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++position;
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} else if (code === 10) {
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// new line
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++position;
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++lexer.line;
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lexer.lineStart = position;
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} else if (code === 13) {
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// carriage return
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if (body.charCodeAt(position + 1) === 10) {
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position += 2;
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} else {
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++position;
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}
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++lexer.line;
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lexer.lineStart = position;
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} else {
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break;
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}
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}
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return position;
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}
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/**
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* Reads a comment token from the source file.
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*
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* #[\u0009\u0020-\uFFFF]*
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*/
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function readComment(source, start, line, col, prev) {
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const body = source.body;
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let code;
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let position = start;
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do {
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code = body.charCodeAt(++position);
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} while (!isNaN(code) && ( // SourceCharacter but not LineTerminator
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code > 0x001f || code === 0x0009));
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return new Token(TokenKind.COMMENT, start, position, line, col, prev, body.slice(start + 1, position));
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}
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/**
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* Reads a number token from the source file, either a float
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* or an int depending on whether a decimal point appears.
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*
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* Int: -?(0|[1-9][0-9]*)
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* Float: -?(0|[1-9][0-9]*)(\.[0-9]+)?((E|e)(+|-)?[0-9]+)?
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*/
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function readNumber(source, start, firstCode, line, col, prev) {
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const body = source.body;
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let code = firstCode;
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let position = start;
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let isFloat = false;
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if (code === 45) {
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// -
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code = body.charCodeAt(++position);
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}
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if (code === 48) {
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// 0
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code = body.charCodeAt(++position);
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if (code >= 48 && code <= 57) {
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throw syntaxError(source, position, `Invalid number, unexpected digit after 0: ${printCharCode(code)}.`);
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}
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} else {
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position = readDigits(source, position, code);
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code = body.charCodeAt(position);
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}
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if (code === 46) {
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// .
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isFloat = true;
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code = body.charCodeAt(++position);
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position = readDigits(source, position, code);
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code = body.charCodeAt(position);
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}
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if (code === 69 || code === 101) {
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// E e
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isFloat = true;
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code = body.charCodeAt(++position);
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if (code === 43 || code === 45) {
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// + -
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code = body.charCodeAt(++position);
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}
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position = readDigits(source, position, code);
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code = body.charCodeAt(position);
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} // Numbers cannot be followed by . or NameStart
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if (code === 46 || isNameStart(code)) {
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throw syntaxError(source, position, `Invalid number, expected digit but got: ${printCharCode(code)}.`);
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}
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return new Token(isFloat ? TokenKind.FLOAT : TokenKind.INT, start, position, line, col, prev, body.slice(start, position));
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}
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/**
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* Returns the new position in the source after reading digits.
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*/
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function readDigits(source, start, firstCode) {
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const body = source.body;
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let position = start;
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let code = firstCode;
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if (code >= 48 && code <= 57) {
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// 0 - 9
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do {
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code = body.charCodeAt(++position);
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} while (code >= 48 && code <= 57); // 0 - 9
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return position;
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}
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throw syntaxError(source, position, `Invalid number, expected digit but got: ${printCharCode(code)}.`);
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}
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/**
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* Reads a string token from the source file.
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*
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* "([^"\\\u000A\u000D]|(\\(u[0-9a-fA-F]{4}|["\\/bfnrt])))*"
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*/
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function readString(source, start, line, col, prev) {
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const body = source.body;
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let position = start + 1;
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let chunkStart = position;
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let code = 0;
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let value = '';
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while (position < body.length && !isNaN(code = body.charCodeAt(position)) && // not LineTerminator
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code !== 0x000a && code !== 0x000d) {
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// Closing Quote (")
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if (code === 34) {
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value += body.slice(chunkStart, position);
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return new Token(TokenKind.STRING, start, position + 1, line, col, prev, value);
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} // SourceCharacter
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if (code < 0x0020 && code !== 0x0009) {
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throw syntaxError(source, position, `Invalid character within String: ${printCharCode(code)}.`);
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}
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++position;
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if (code === 92) {
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// \
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value += body.slice(chunkStart, position - 1);
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code = body.charCodeAt(position);
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switch (code) {
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case 34:
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value += '"';
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break;
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case 47:
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value += '/';
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break;
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case 92:
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value += '\\';
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break;
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case 98:
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value += '\b';
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break;
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case 102:
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value += '\f';
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break;
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case 110:
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value += '\n';
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break;
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case 114:
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value += '\r';
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break;
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case 116:
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value += '\t';
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break;
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case 117:
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{
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// uXXXX
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const charCode = uniCharCode(body.charCodeAt(position + 1), body.charCodeAt(position + 2), body.charCodeAt(position + 3), body.charCodeAt(position + 4));
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if (charCode < 0) {
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const invalidSequence = body.slice(position + 1, position + 5);
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throw syntaxError(source, position, `Invalid character escape sequence: \\u${invalidSequence}.`);
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}
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value += String.fromCharCode(charCode);
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position += 4;
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break;
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}
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default:
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throw syntaxError(source, position, `Invalid character escape sequence: \\${String.fromCharCode(code)}.`);
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}
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++position;
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chunkStart = position;
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}
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}
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throw syntaxError(source, position, 'Unterminated string.');
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}
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/**
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* Reads a block string token from the source file.
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*
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* """("?"?(\\"""|\\(?!=""")|[^"\\]))*"""
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*/
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function readBlockString(source, start, line, col, prev, lexer) {
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const body = source.body;
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let position = start + 3;
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let chunkStart = position;
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let code = 0;
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let rawValue = '';
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while (position < body.length && !isNaN(code = body.charCodeAt(position))) {
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// Closing Triple-Quote (""")
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if (code === 34 && body.charCodeAt(position + 1) === 34 && body.charCodeAt(position + 2) === 34) {
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rawValue += body.slice(chunkStart, position);
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return new Token(TokenKind.BLOCK_STRING, start, position + 3, line, col, prev, dedentBlockStringValue(rawValue));
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} // SourceCharacter
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if (code < 0x0020 && code !== 0x0009 && code !== 0x000a && code !== 0x000d) {
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throw syntaxError(source, position, `Invalid character within String: ${printCharCode(code)}.`);
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}
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if (code === 10) {
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// new line
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++position;
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++lexer.line;
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lexer.lineStart = position;
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} else if (code === 13) {
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// carriage return
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if (body.charCodeAt(position + 1) === 10) {
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position += 2;
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} else {
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++position;
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}
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++lexer.line;
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lexer.lineStart = position;
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} else if ( // Escape Triple-Quote (\""")
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code === 92 && body.charCodeAt(position + 1) === 34 && body.charCodeAt(position + 2) === 34 && body.charCodeAt(position + 3) === 34) {
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rawValue += body.slice(chunkStart, position) + '"""';
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position += 4;
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chunkStart = position;
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} else {
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++position;
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}
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}
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throw syntaxError(source, position, 'Unterminated string.');
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}
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/**
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* Converts four hexadecimal chars to the integer that the
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* string represents. For example, uniCharCode('0','0','0','f')
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* will return 15, and uniCharCode('0','0','f','f') returns 255.
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*
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* Returns a negative number on error, if a char was invalid.
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*
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* This is implemented by noting that char2hex() returns -1 on error,
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* which means the result of ORing the char2hex() will also be negative.
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*/
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function uniCharCode(a, b, c, d) {
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return char2hex(a) << 12 | char2hex(b) << 8 | char2hex(c) << 4 | char2hex(d);
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}
|
|
/**
|
|
* Converts a hex character to its integer value.
|
|
* '0' becomes 0, '9' becomes 9
|
|
* 'A' becomes 10, 'F' becomes 15
|
|
* 'a' becomes 10, 'f' becomes 15
|
|
*
|
|
* Returns -1 on error.
|
|
*/
|
|
|
|
|
|
function char2hex(a) {
|
|
return a >= 48 && a <= 57 ? a - 48 // 0-9
|
|
: a >= 65 && a <= 70 ? a - 55 // A-F
|
|
: a >= 97 && a <= 102 ? a - 87 // a-f
|
|
: -1;
|
|
}
|
|
/**
|
|
* Reads an alphanumeric + underscore name from the source.
|
|
*
|
|
* [_A-Za-z][_0-9A-Za-z]*
|
|
*/
|
|
|
|
|
|
function readName(source, start, line, col, prev) {
|
|
const body = source.body;
|
|
const bodyLength = body.length;
|
|
let position = start + 1;
|
|
let code = 0;
|
|
|
|
while (position !== bodyLength && !isNaN(code = body.charCodeAt(position)) && (code === 95 || // _
|
|
code >= 48 && code <= 57 || // 0-9
|
|
code >= 65 && code <= 90 || // A-Z
|
|
code >= 97 && code <= 122) // a-z
|
|
) {
|
|
++position;
|
|
}
|
|
|
|
return new Token(TokenKind.NAME, start, position, line, col, prev, body.slice(start, position));
|
|
} // _ A-Z a-z
|
|
|
|
|
|
function isNameStart(code) {
|
|
return code === 95 || code >= 65 && code <= 90 || code >= 97 && code <= 122;
|
|
} |