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expression-compiler
Advanced tools
Compile math expressions to a useful AST, with built-in compilers to turn the AST into a sanitized javascript function.
$ npm install expression-compiler
and also get the raw js generated for the function
> var mkFunc = require('expression-compiler/func');
undefined
> var expressionFunc = compile('c*sin(2*t)+1');
undefined
> expressionFunc({c: 0.5});
0.9999999999999999
> mkFunc.express('sqrt(x^2 + y^2)')
'(Math.sqrt((Math.pow(symbols["x"],2.0)+Math.pow(symbols["y"],2.0))))'
Note that everything in the global Math
is made available by the built-in function compiler, and it is assumed that the global Math
assumed available by its express
function.
and then echo back the original expression with just the AST
> var parse = require('expression-compiler/parse');
undefind
> var ast = parse('sin(t)^2 + cos(t)^2');
unefined
> ast
{ id: 0,
type: 'ASTNode',
node: 'expr',
template: '#',
children:
[ { id: 1,
type: 'ASTNode',
node: 'func',
template: '# +#',
children: [Object],
options: [Object] } ],
options: {} }
> console.log(JSON.stringify(ast, null, 2)); // print out the whole thing
{
"id": 0,
"type": "ASTNode",
"node": "expr",
"template": "#",
"children": [
{
"id": 1,
"type": "ASTNode",
"node": "func",
"template": "# +#",
"children": [
{
"id": 2,
"type": "ASTNode",
"node": "func",
"template": "#^#",
"children": [
{
"id": 3,
"type": "ASTNode",
"node": "func",
"template": "sin(#)",
"children": [
{
"id": 4,
"type": "ASTNode",
"node": "name",
"template": "t",
"children": [],
"options": {
"key": "t"
}
}
],
"options": {
"key": "sin"
}
},
{
"id": 5,
"type": "ASTNode",
"node": "literal",
"template": "2",
"children": [],
"options": {
"value": 2
}
}
],
"options": {
"key": "pow"
}
},
{
"id": 6,
"type": "ASTNode",
"node": "func",
"template": "#^#",
"children": [
{
"id": 7,
"type": "ASTNode",
"node": "func",
"template": " cos(#)",
"children": [
{
"id": 8,
"type": "ASTNode",
"node": "name",
"template": "t",
"children": [],
"options": {
"key": "t"
}
}
],
"options": {
"key": "cos"
}
},
{
"id": 9,
"type": "ASTNode",
"node": "literal",
"template": "2",
"children": [],
"options": {
"value": 2
}
}
],
"options": {
"key": "pow"
}
}
],
"options": {
"key": "sum"
}
}
],
"options": {}
}
undefined
> var echoer = require('expression-compiler/echo');
undefined
> echoer.fromAST(ast);
'sin(t)^2 + cos(t)^2'
New AST node design:
{
id: 0,
type: 'ASTNode',
node: 'expr',
template: '#',
children: [],
options: {}
}
id
must be uniquetype
must be a valid node typeoptions
contains different properties depending on the node typeexpr
options:
{}
func
options:
{
key: 'funcName'
}
Infix functions should be normal function nodes. Here are some examples for +
with 2 or 3 operands:
{
id: 0,
type: 'ASTNode',
node: 'func',
template: '# + # + #',
children: [someNode, anotherNode, andAnother],
options: {
key: 'sum'
}
}
Normal functions can take multiple arguments
{
id: 0,
type: 'ASTNode',
node: 'func',
template: 'min(#, #)',
children: [someNode, anotherNode],
options: {
key: 'min'
}
}
name
options:
{
key: 'varName'
}
literal
options:
{
value: 1
}
FAQs
Expression Compiler ===================
The npm package expression-compiler receives a total of 0 weekly downloads. As such, expression-compiler popularity was classified as not popular.
We found that expression-compiler demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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