Flatten an Abstract Syntax Tree by placing all the nodes in a single flat array.
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npm install flastRequires Node 16 or newer.
git clone [email protected]:PerimeterX/flast.git
cd flast
npm install- Keeps all relations between parent and child nodes.
- Tracks scope and connects each declaration to its references.
See eslint-scope for more info on the scopes used. - Adds a unique id to each node to simplify tracking and understanding relations between nodes.
- Arborist - marks nodes for replacement or deletion and applies all changes in a single iteration over the tree.
Example of how a flat AST would look like.
Input code: console.log('flAST');.
Output object:
const tree = [
{
type: 'program',
start: 0,
end: 21,
range: [0, 21],
body: [
'<ref to nodeId#2>'
],
sourceType: 'script',
comments: [],
nodeId: 0,
src: "console.log('flAST');",
childNodes: [
'<ref to nodeId#1>'
],
parentNode: null,
scope: '<GlobalScope scopeId#0>'
},
{
type: 'ExpressionStatement',
start: 0,
end: 21,
range: [0, 21],
expression: '<ref to nodeId#2>',
nodeId: 1,
src: "console.log('flAST');",
childNodes: [
'<ref to nodeId#2>'
],
parentNode: '<ref to nodeId#0>',
scope: '<GlobalScope scopeId#0>'
},
{
type: 'CallExpression',
start: 0,
end: 20,
range: [0, 20],
callee: '<ref to nodeId#3>',
arguments: [
'<ref to nodeId#6>'
],
optional: false,
nodeId: 2,
src: "console.log('flAST')",
childNodes: [
'<ref to nodeId#3>',
'<ref to nodeId#6>'
],
parentNode: '<ref to nodeId#1>',
scope: '<GlobalScope scopeId#0>'
},
{
type: 'MemberExpression',
start: 0,
end: 11,
range: [0, 11],
object: '<ref to nodeId#4>',
property: '<ref to nodeId#5>',
computed: false,
optional: false,
nodeId: 3,
src: 'console.log',
childNodes: [
'<ref to nodeId#4>',
'<ref to nodeId#5>'
],
parentNode: '<ref to nodeId#2>',
scope: '<GlobalScope scopeId#0>'
},
{
type: 'Identifier',
start: 0,
end: 7,
range: [0, 7],
name: 'console',
nodeId: 4,
src: 'console',
childNodes: [],
parentNode: '<ref to nodeId#3>',
scope: '<GlobalScope scopeId#0>'
},
{
type: 'Identifier',
start: 8,
end: 11,
range: [8, 11],
name: 'log',
nodeId: 5,
src: 'log',
childNodes: [],
parentNode: '<ref to nodeId#3>',
scope: '<GlobalScope scopeId#0>'
},
{
type: 'Literal',
start: 12,
end: 19,
range: [12, 19],
value: "flAST",
raw: "'flAST'",
nodeId: 6,
src: "'flAST'",
childNodes: [],
parentNode: '<ref to nodeId#2>',
scope: '<GlobalScope scopeId#0>'
}
];const {generateFlatAST, generateCode} = require('flast');
const ast = generateFlatAST(`console.log('flAST')`);
const reconstructedCode = generateCode(ast[0]); // rebuild from root nodeconst generateFlatASTDefaultOptions = {
detailed: true, // If false, include only original node without any further details
includeSrc: true, // If false, do not include node src. Only available when `detailed` option is true
};See Espree's documentation for more information
const generateCodeDefaultOptions = {
format: {
indent: {
style: ' ',
adjustMultilineComment: true,
},
quotes: 'auto',
escapeless: true,
compact: false,
},
comment: true,
};const {generateFlatAST, generateCode, Arborist} = require('flast');
const ast = generateFlatAST(`console.log('Hello' + ' ' + 'there!');`);
const replacements = {
'Hello': 'General',
'there!': 'Kenobi',
};
const arborist = new Arborist(ast);
// Mark all relevant nodes for replacement.
ast.filter(n => n.type === 'Literal' && replacements[n.value]).forEach(n => arborist.markNode(n, {
type: 'Literal',
value: replacements[n.value],
raw: `'${replacements[n.value]}'`,
}));
const numberOfChangesMade = arborist.applyChanges();
console.log(generateCode(arborist.ast[0])); // console.log('General' + ' ' + 'Kenobi');The Arborist can be called with an extra argument - logFunc - which can be used to log inside the arborist.
To contribute to this project see our contribution guide
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