js-slang
Version:
Javascript-based implementations of Source, written in Typescript
87 lines • 3.89 kB
JavaScript
;
/**
* The main entry point of the scheme transpiler.
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.schemeParse = exports.ParserError = exports.LexerError = void 0;
const lexer_1 = require("./lexer");
const parser_1 = require("./parser");
const scheme_node_types_1 = require("./types/nodes/scheme-node-types");
const visitors_1 = require("./visitors");
const __1 = require("..");
const constants_1 = require("./types/constants");
var lexer_2 = require("./lexer");
Object.defineProperty(exports, "LexerError", { enumerable: true, get: function () { return lexer_2.LexerError; } });
var parser_2 = require("./parser");
Object.defineProperty(exports, "ParserError", { enumerable: true, get: function () { return parser_2.ParserError; } });
/**
* wrap an s-expression in an eval call.
*/
function wrapInEval(body) {
const evalObj = new scheme_node_types_1.Atomic.Identifier(body.location, "eval");
return new scheme_node_types_1.Atomic.Application(body.location, evalObj, [body]);
}
/**
* wrap an s-expression in a begin statement.
* since we want an s-expression as return,
* begin is represented as a list of expressions starting with "begin".
*/
function wrapInBegin(expressions) {
// use the total location of the first and last expressions
const dummyloc = expressions[0].location.merge(expressions[expressions.length - 1].location);
const begin = new scheme_node_types_1.Atomic.Symbol(dummyloc, "begin");
return new scheme_node_types_1.Extended.List(dummyloc, [begin, ...expressions]);
}
/**
* Transpiles Scheme source code into an ESTree program.
* @param source The Scheme source code
* @param chapter The chapter of the Scheme language.
* If not provided, defaults to the latest version.
* @returns
*/
function schemeParse(source, chapter = Infinity, encode) {
// Instantiate the lexer
const lexer = new lexer_1.SchemeLexer(source);
// Generate tokens
const tokens = lexer.scanTokens();
// Instantiate the parser
const parser = new parser_1.SchemeParser(source, tokens, chapter);
// The Scheme AST is represented as an
// array of expressions, which is all top-level expressions
let finalAST;
// Generate the first AST
const firstAST = parser.parse();
// We instantiate all the visitors
const simplifier = visitors_1.Simplifier.create();
const redefiner = visitors_1.Redefiner.create();
const transpiler = visitors_1.Transpiler.create();
if (chapter < constants_1.MACRO_CHAPTER) {
// Then we simplify the AST
const simplifiedAST = simplifier.simplify(firstAST);
// Then we redefine the AST
const redefinedAST = redefiner.redefine(simplifiedAST);
finalAST = redefinedAST;
}
else {
// Then we prepare the AST for evaluation within the CSET machine.
// Take the imports from the AST
const macroASTImports = firstAST.filter(e => e instanceof scheme_node_types_1.Atomic.Import);
const macroASTRest = firstAST.filter(e => !(e instanceof scheme_node_types_1.Atomic.Import));
// On the rest elements,
// 1. If empty, do nothing
// 2. If 1 element, wrap in eval call
// 3. If more than one element, sequence as one begin statement, then wrap in eval call
const macroASTformattedRest = macroASTRest.length === 0
? []
: macroASTRest.length === 1
? [wrapInEval(macroASTRest[0])]
: [wrapInEval(wrapInBegin(macroASTRest))];
// Concatenate the imports and the rest
finalAST = [...macroASTImports, ...macroASTformattedRest];
}
// Finally we transpile the AST
const program = transpiler.transpile(finalAST);
return encode ? (0, __1.estreeEncode)(program) : program;
}
exports.schemeParse = schemeParse;
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