559 lines
19 KiB
JavaScript
559 lines
19 KiB
JavaScript
/*
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* Copyright (C) 2016 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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"use strict";
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function parse(tokenizer)
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{
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let program;
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let pushBackBuffer = [];
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function nextToken()
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{
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if (pushBackBuffer.length)
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return pushBackBuffer.pop();
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let result = tokenizer.next();
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if (result.done)
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return {kind: "endOfFile", string: "<end of file>"};
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return result.value;
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}
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function pushToken(token)
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{
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pushBackBuffer.push(token);
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}
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function peekToken()
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{
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let result = nextToken();
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pushToken(result);
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return result;
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}
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function consumeKind(kind)
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{
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let token = nextToken();
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if (token.kind != kind) {
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throw new Error("At " + token.sourceLineNumber + ": expected " + kind + " but got: " + token.string);
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}
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return token;
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}
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function consumeToken(string)
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{
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let token = nextToken();
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if (token.string.toLowerCase() != string.toLowerCase())
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throw new Error("At " + token.sourceLineNumber + ": expected " + string + " but got: " + token.string);
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return token;
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}
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function parseVariable()
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{
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let name = consumeKind("identifier").string;
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let result = {evaluate: Basic.Variable, name, parameters: []};
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if (peekToken().string == "(") {
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do {
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nextToken();
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result.parameters.push(parseNumericExpression());
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} while (peekToken().string == ",");
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consumeToken(")");
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}
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return result;
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}
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function parseNumericExpression()
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{
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function parsePrimary()
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{
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let token = nextToken();
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switch (token.kind) {
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case "identifier": {
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let result = {evaluate: Basic.NumberApply, name: token.string, parameters: []};
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if (peekToken().string == "(") {
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do {
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nextToken();
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result.parameters.push(parseNumericExpression());
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} while (peekToken().string == ",");
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consumeToken(")");
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}
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return result;
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}
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case "number":
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return {evaluate: Basic.Const, value: token.value};
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case "operator":
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switch (token.string) {
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case "(": {
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let result = parseNumericExpression();
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consumeToken(")");
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return result;
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} }
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break;
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}
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throw new Error("At " + token.sourceLineNumber + ": expected identifier, number, or (, but got: " + token.string);
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}
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function parseFactor()
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{
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let primary = parsePrimary();
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let ok = true;
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while (ok) {
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switch (peekToken().string) {
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case "^":
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nextToken();
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primary = {evaluate: Basic.NumberPow, left: primary, right: parsePrimary()};
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break;
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default:
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ok = false;
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break;
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}
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}
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return primary;
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}
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function parseTerm()
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{
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let factor = parseFactor();
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let ok = true;
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while (ok) {
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switch (peekToken().string) {
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case "*":
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nextToken();
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factor = {evaluate: Basic.NumberMul, left: factor, right: parseFactor()};
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break;
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case "/":
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nextToken();
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factor = {evaluate: Basic.NumberDiv, left: factor, right: parseFactor()};
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break;
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default:
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ok = false;
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break;
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}
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}
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return factor;
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}
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// Only the leading term in Basic can have a sign.
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let negate = false;
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switch (peekToken().string) {
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case "+":
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nextToken();
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break;
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case "-":
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negate = true;
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nextToken()
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break;
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}
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let term = parseTerm();
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if (negate)
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term = {evaluate: Basic.NumberNeg, term: term};
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let ok = true;
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while (ok) {
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switch (peekToken().string) {
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case "+":
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nextToken();
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term = {evaluate: Basic.NumberAdd, left: term, right: parseTerm()};
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break;
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case "-":
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nextToken();
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term = {evaluate: Basic.NumberSub, left: term, right: parseTerm()};
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break;
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default:
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ok = false;
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break;
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}
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}
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return term;
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}
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function parseConstant()
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{
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switch (peekToken().string) {
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case "+":
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nextToken();
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return consumeKind("number").value;
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case "-":
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nextToken();
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return -consumeKind("number").value;
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default:
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if (isStringExpression())
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return consumeKind("string").value;
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return consumeKind("number").value;
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}
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}
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function parseStringExpression()
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{
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let token = nextToken();
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switch (token.kind) {
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case "string":
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return {evaluate: Basic.Const, value: token.value};
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case "identifier":
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consumeToken("$");
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return {evaluate: Basic.StringVar, name: token.string};
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default:
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throw new Error("At " + token.sourceLineNumber + ": expected string expression but got " + token.string);
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}
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}
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function isStringExpression()
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{
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// A string expression must start with a string variable or a string constant.
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let token = nextToken();
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if (token.kind == "string") {
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pushToken(token);
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return true;
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}
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if (token.kind == "identifier") {
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let result = peekToken().string == "$";
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pushToken(token);
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return result;
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}
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pushToken(token);
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return false;
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}
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function parseRelationalExpression()
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{
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if (isStringExpression()) {
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let left = parseStringExpression();
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let operator = nextToken();
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let evaluate;
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switch (operator.string) {
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case "=":
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evaluate = Basic.Equals;
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break;
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case "<>":
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evaluate = Basic.NotEquals;
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break;
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default:
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throw new Error("At " + operator.sourceLineNumber + ": expected a string comparison operator but got: " + operator.string);
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}
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return {evaluate, left, right: parseStringExpression()};
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}
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let left = parseNumericExpression();
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let operator = nextToken();
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let evaluate;
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switch (operator.string) {
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case "=":
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evaluate = Basic.Equals;
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break;
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case "<>":
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evaluate = Basic.NotEquals;
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break;
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case "<":
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evaluate = Basic.LessThan;
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break;
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case ">":
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evaluate = Basic.GreaterThan;
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break;
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case "<=":
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evaluate = Basic.LessEqual;
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break;
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case ">=":
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evaluate = Basic.GreaterEqual;
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break;
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default:
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throw new Error("At " + operator.sourceLineNumber + ": expected a numeric comparison operator but got: " + operator.string);
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}
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return {evaluate, left, right: parseNumericExpression()};
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}
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function parseNonNegativeInteger()
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{
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let token = nextToken();
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if (!/^[0-9]+$/.test(token.string))
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throw new Error("At ", token.sourceLineNumber + ": expected a line number but got: " + token.string);
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return token.value;
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}
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function parseGoToStatement()
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{
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statement.kind = Basic.GoTo;
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statement.target = parseNonNegativeInteger();
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}
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function parseGoSubStatement()
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{
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statement.kind = Basic.GoSub;
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statement.target = parseNonNegativeInteger();
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}
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function parseStatement()
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{
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let statement = {};
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statement.lineNumber = consumeKind("userLineNumber").userLineNumber;
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program.statements.set(statement.lineNumber, statement);
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let command = nextToken();
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statement.sourceLineNumber = command.sourceLineNumber;
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switch (command.kind) {
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case "keyword":
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switch (command.string.toLowerCase()) {
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case "def":
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statement.process = Basic.Def;
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statement.name = consumeKind("identifier");
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statement.parameters = [];
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if (peekToken().string == "(") {
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do {
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nextToken();
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statement.parameters.push(consumeKind("identifier"));
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} while (peekToken().string == ",");
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}
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statement.expression = parseNumericExpression();
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break;
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case "let":
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statement.process = Basic.Let;
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statement.variable = parseVariable();
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consumeToken("=");
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if (statement.process == Basic.Let)
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statement.expression = parseNumericExpression();
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else
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statement.expression = parseStringExpression();
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break;
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case "go": {
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let next = nextToken();
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if (next.string == "to")
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parseGoToStatement();
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else if (next.string == "sub")
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parseGoSubStatement();
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else
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throw new Error("At " + next.sourceLineNumber + ": expected to or sub but got: " + next.string);
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break;
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}
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case "goto":
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parseGoToStatement();
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break;
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case "gosub":
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parseGoSubStatement();
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break;
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case "if":
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statement.process = Basic.If;
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statement.condition = parseRelationalExpression();
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consumeToken("then");
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statement.target = parseNonNegativeInteger();
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break;
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case "return":
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statement.process = Basic.Return;
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break;
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case "stop":
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statement.process = Basic.Stop;
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break;
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case "on":
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statement.process = Basic.On;
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statement.expression = parseNumericExpression();
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if (peekToken().string == "go") {
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consumeToken("go");
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consumeToken("to");
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} else
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consumeToken("goto");
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statement.targets = [];
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for (;;) {
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statement.targets.push(parseNonNegativeInteger());
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if (peekToken().string != ",")
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break;
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nextToken();
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}
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break;
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case "for":
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statement.process = Basic.For;
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statement.variable = consumeKind("identifier").string;
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consumeToken("=");
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statement.initial = parseNumericExpression();
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consumeToken("to");
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statement.limit = parseNumericExpression();
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if (peekToken().string == "step") {
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nextToken();
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statement.step = parseNumericExpression();
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} else
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statement.step = {evaluate: Basic.Const, value: 1};
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consumeKind("newLine");
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let lastStatement = parseStatements();
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if (lastStatement.process != Basic.Next)
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throw new Error("At " + lastStatement.sourceLineNumber + ": expected next statement");
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if (lastStatement.variable != statement.variable)
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throw new Error("At " + lastStatement.sourceLineNumber + ": expected next for " + statement.variable + " but got " + lastStatement.variable);
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lastStatement.target = statement;
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statement.target = lastStatement;
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return statement;
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case "next":
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statement.process = Basic.Next;
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statement.variable = consumeKind("identifier").string;
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break;
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case "print": {
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statement.process = Basic.Print;
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statement.items = [];
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let ok = true;
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while (ok) {
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switch (peekToken().string) {
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case ",":
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nextToken();
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statement.items.push({kind: "comma"});
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break;
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case ";":
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nextToken();
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break;
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case "tab":
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nextToken();
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consumeToken("(");
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statement.items.push({kind: "tab", value: parseNumericExpression()});
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break;
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case "\n":
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ok = false;
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break;
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default:
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if (isStringExpression()) {
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statement.items.push({kind: "string", value: parseStringExpression()});
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break;
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}
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statement.items.push({kind: "number", value: parseNumericExpression()});
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break;
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}
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}
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break;
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}
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case "input":
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statement.process = Basic.Input;
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statement.items = [];
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for (;;) {
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stament.items.push(parseVariable());
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if (peekToken().string != ",")
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break;
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nextToken();
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}
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break;
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case "read":
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statement.process = Basic.Read;
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statement.items = [];
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for (;;) {
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stament.items.push(parseVariable());
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if (peekToken().string != ",")
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break;
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nextToken();
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}
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break;
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case "restore":
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statement.process = Basic.Restore;
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break;
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case "data":
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for (;;) {
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program.data.push(parseConstant());
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if (peekToken().string != ",")
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break;
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nextToken();
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}
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break;
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case "dim":
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statement.process = Basic.Dim;
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statement.items = [];
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for (;;) {
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let name = consumeKind("identifier").string;
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consumeToken("(");
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let bounds = [];
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bounds.push(parseNonNegativeInteger());
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if (peekToken().string == ",") {
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nextToken();
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bounds.push(parseNonNegativeInteger());
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}
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consumeToken(")");
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statement.items.push({name, bounds});
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if (peekToken().string != ",")
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break;
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consumeToken(",");
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}
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break;
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case "option": {
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consumeToken("base");
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let base = parseNonNegativeInteger();
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if (base != 0 && base != 1)
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throw new Error("At " + command.sourceLineNumber + ": unexpected base: " + base);
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program.base = base;
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break;
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}
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case "randomize":
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statement.process = Basic.Randomize;
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break;
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case "end":
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statement.process = Basic.End;
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break;
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default:
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throw new Error("At " + command.sourceLineNumber + ": unexpected command but got: " + command.string);
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}
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break;
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case "remark":
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// Just ignore it.
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break;
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default:
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throw new Error("At " + command.sourceLineNumber + ": expected command but got: " + command.string + " (of kind " + command.kind + ")");
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}
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consumeKind("newLine");
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return statement;
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}
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function parseStatements()
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{
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let statement;
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do {
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statement = parseStatement();
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} while (!statement.process || !statement.process.isBlockEnd);
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return statement;
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}
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return {
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program()
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{
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program = {
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process: Basic.Program,
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statements: new Map(),
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data: [],
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base: 0
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};
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let lastStatement = parseStatements(program.statements);
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if (lastStatement.process != Basic.End)
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throw new Error("At " + lastStatement.sourceLineNumber + ": expected end");
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return program;
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},
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statement(program_)
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{
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program = program_;
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return parseStatement();
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}
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};
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}
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