This is a minimalistic experiment with CTFE to generate performant code while maintaining expressiveness.
Main goals:
- Lightweight dynamic transpilation of a few selected ECMAScript features for older browsers like IE11.
- Easy dynamic generation of performant math and/or repetitive code, where needed (don't abuse...).
- Build-time transformation, i.e.
ct.jsmay easily be integrated into a build system.
Contents:
// --- Statement examples `ct...ct;`
const _wr = (name) => `console.log("${name}",${name})`;
(function () {
// Pure function: no closure needed
const f = ct( (x) => { ct.mix(_wr("x")).ct; } );
console.log(f);
// js console output: ((x) => { console.log("x",x); })
f(123); // js console output: x 123
f(456); // js console output: x 456
f(789); // js console output: x 789
})();
(function () {
// Closure needed: use `eval(''+ct(...))`
var x = 1.234;
const g = eval( ''+ct( () => { ct.mix(_wr("x++")).ct; } ) );
console.log(g);
// js console output: () => { console.log("x++",x++); }
g(); // js console output: x++ 1.234
g(); // js console output: x++ 2.234
g(); // js console output: x++ 3.234
})();
// In fact, there is a shortcut for that particular `_wr` case
// (useful for debugging code)
(function () {
// Pure function: no closure needed
const f = ct( (x) => { ct.wr(x).ct; } );
console.log(f);
// js console output: ((x) => { console.log("x",x); })
f(123); // js console output: x 123
f(456); // js console output: x 456
f(789); // js console output: x 789
})();
(function () {
// Closure needed: use `eval(''+ct(...))`
var x = 1.234;
const g = eval( ''+ct( () => { ct.wr(x++).ct; } ) );
console.log(g);
// js console output: () => { console.log("x++",x++); }
g(); // js console output: x++ 1.234
g(); // js console output: x++ 2.234
g(); // js console output: x++ 3.234
})();
// --- Expression examples `ct...ct`
(function () {
// see also: ct.last
const h = ct( arr => ct.at( arr[$-1] ).ct + 3.45 );
h( [ 10.0, 20.0, 30.0, 40.0 ] ) === 43.45 || null.bug;
})();
(function () {
const h = ct( ( a, b, c ) =>
{
// Local CT definition. These 3 lines are removed
// by the `ct()` call.
ct.def( function expr( /*string*/x, /*string*/y, /*string*/z ) {
return `(${x}+${y})/(${y}-${z})*${z}*${z}`;
}).ct
return [
ct.expr( 'a', 'b', 'c' ).ct
, ct.expr( 'a', 'c', 'b' ).ct
, ct.expr( 'b', 'a', 'c' ).ct
, ct.expr( 'b', 'c', 'a' ).ct
, ct.expr( 'c', 'a', 'b' ).ct
, ct.expr( 'c', 'b', 'a' ).ct
];
} );
console.log( ''+h );
/* js console output:
(( a, b, c ) =>
{
// Local CT definition. These 3 lines are removed
// by the `ct()` call.
return [
(a+b)/(b-c)*c*c
, (a+c)/(c-b)*b*b
, (b+a)/(a-c)*c*c
, (b+c)/(c-a)*a*a
, (c+a)/(a-b)*b*b
, (c+b)/(b-a)*a*a
];
})
*/
console.log( h( 1.0, 2.0, 3.0 ) );
// js console output: [-27, 16, -13.5, 2.5, -16, 5]
h( 1.0, 2.0, 3.0 ).join(',')
=== [-27, 16, -13.5, 2.5, -16, 5].join(',')
|| null.bug;
})();
(function () {
// Variant with ct.emap, and a short definition of `expr`
const h = ct( ( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
ct.def( expr, ( x, y, z ) => `(${x}+${y})/(${y}-${z})*${z}*${z}` ).ct
return ct.emap(expr)([
[ 'a', 'b', 'c' ]
, [ 'a', 'c', 'b' ]
, [ 'b', 'a', 'c' ]
, [ 'b', 'c', 'a' ]
, [ 'c', 'a', 'b' ]
, [ 'c', 'b', 'a' ]
]).ct;
} );
console.log( ''+h );
/* js console output:
(( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
return [(a+b)/(b-c)*c*c
, (a+c)/(c-b)*b*b
, (b+a)/(a-c)*c*c
, (b+c)/(c-a)*a*a
, (c+a)/(a-b)*b*b
, (c+b)/(b-a)*a*a];
})
*/
console.log( h( 1.0, 2.0, 3.0 ) );
// js console output: [-27, 16, -13.5, 2.5, -16, 5]
h( 1.0, 2.0, 3.0 ).join(',')
=== [-27, 16, -13.5, 2.5, -16, 5].join(',')
|| null.bug;
})();
const CONSTANT = [
[ 'a', 'b', 'c' ]
, [ 'a', 'c', 'b' ]
, [ 'b', 'a', 'c' ]
, [ 'b', 'c', 'a' ]
, [ 'c', 'a', 'b' ]
, [ 'c', 'b', 'a' ]
];
(function () {
// Variant with ct.emap, and a short definition of `expr` and a
// global constant
const h = ct( ( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
ct.def( expr, ( x, y, z ) => `(${x}+${y})/(${y}-${z})*${z}*${z}` ).ct
return ct.emap(expr)( CONSTANT ).ct;
} );
console.log( ''+h );
/* js console output:
(( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
return [(a+b)/(b-c)*c*c
, (a+c)/(c-b)*b*b
, (b+a)/(a-c)*c*c
, (b+c)/(c-a)*a*a
, (c+a)/(a-b)*b*b
, (c+b)/(b-a)*a*a];
})
*/
console.log( h( 1.0, 2.0, 3.0 ) );
// js console output: [-27, 16, -13.5, 2.5, -16, 5]
h( 1.0, 2.0, 3.0 ).join(',')
=== [-27, 16, -13.5, 2.5, -16, 5].join(',')
|| null.bug;
})();
(function () {
const h = ct( ( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
ct.def( expr, ( x, y, z ) => `(${x}+${y})/(${y}-${z})*${z}*${z}` ).ct
return ct.emap(expr)({
p : [ 'a', 'b', 'c' ]
, q : [ 'a', 'c', 'b' ]
, r : [ 'b', 'a', 'c' ]
, s : [ 'b', 'c', 'a' ]
, t : [ 'c', 'a', 'b' ]
, u : [ 'c', 'b', 'a' ]
}).ct;
} );
console.log( ''+h );
/* js console output:
(( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
return {p : (a+b)/(b-c)*c*c
, q : (a+c)/(c-b)*b*b
, r : (b+a)/(a-c)*c*c
, s : (b+c)/(c-a)*a*a
, t : (c+a)/(a-b)*b*b
, u : (c+b)/(b-a)*a*a};
})
*/
console.log( h( 1.0, 2.0, 3.0 ) );
// js console output: {p:-27, q:16, r:-13.5, s:2.5, t:-16, u:5}
JSON.stringify(h( 1.0, 2.0, 3.0 ))
=== JSON.stringify({p:-27, q:16, r:-13.5, s:2.5, t:-16, u:5})
|| null.bug;
})();
(function () {
// Variant with ct.emap, a short definition of `expr`, and
// shortcut comma-separated strings like 'a,b,c'.
const h = ct( ( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
ct.def( expr, ( x, y, z ) => `(${x}+${y})/(${y}-${z})*${z}*${z}` ).ct
return ct.emap(expr)([
'a,b,c'
, 'a,c,b'
, 'b,a,c'
, 'b,c,a'
, 'c,a,b'
, 'c,b,a'
]).ct;
} );
console.log( ''+h );
/* js console output:
(( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
return [(a+b)/(b-c)*c*c
, (a+c)/(c-b)*b*b
, (b+a)/(a-c)*c*c
, (b+c)/(c-a)*a*a
, (c+a)/(a-b)*b*b
, (c+b)/(b-a)*a*a];
})
*/
console.log( h( 1.0, 2.0, 3.0 ) );
// js console output: [-27, 16, -13.5, 2.5, -16, 5]
h( 1.0, 2.0, 3.0 ).join(',')
=== [-27, 16, -13.5, 2.5, -16, 5].join(',')
|| null.bug;
})();
const CONSTANT2 = [
'a,b,c'
, 'a,c,b'
, 'b,a,c'
, 'b,c,a'
, 'c,a,b'
, 'c,b,a'
];
(function () {
// Variant with ct.emap, a short definition of `expr`, a global
// constant, and shortcut comma-separated strings like 'a,b,c'.
const h = ct( ( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
ct.def( expr, ( x, y, z ) => `(${x}+${y})/(${y}-${z})*${z}*${z}` ).ct
return ct.emap(expr)( CONSTANT ).ct;
} );
console.log( ''+h );
/* js console output:
(( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
return [(a+b)/(b-c)*c*c
, (a+c)/(c-b)*b*b
, (b+a)/(a-c)*c*c
, (b+c)/(c-a)*a*a
, (c+a)/(a-b)*b*b
, (c+b)/(b-a)*a*a];
})
*/
console.log( h( 1.0, 2.0, 3.0 ) );
// js console output: [-27, 16, -13.5, 2.5, -16, 5]
h( 1.0, 2.0, 3.0 ).join(',')
=== [-27, 16, -13.5, 2.5, -16, 5].join(',')
|| null.bug;
})();
(function () {
const h = ct( ( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
ct.def( expr, ( x, y, z ) => `(${x}+${y})/(${y}-${z})*${z}*${z}` ).ct
return ct.emap(expr)({
p : 'a,b,c'
, q : 'a,c,b'
, r : 'b,a,c'
, s : 'b,c,a'
, t : 'c,a,b'
, u : 'c,b,a'
}).ct;
} );
console.log( ''+h );
/* js console output:
(( a, b, c ) =>
{
// Local CT definition. The next line is removed
// by the `ct()` call.
return {p : (a+b)/(b-c)*c*c
, q : (a+c)/(c-b)*b*b
, r : (b+a)/(a-c)*c*c
, s : (b+c)/(c-a)*a*a
, t : (c+a)/(a-b)*b*b
, u : (c+b)/(b-a)*a*a};
})
*/
console.log( h( 1.0, 2.0, 3.0 ) );
// js console output: {p:-27, q:16, r:-13.5, s:2.5, t:-16, u:5}
JSON.stringify(h( 1.0, 2.0, 3.0 ))
=== JSON.stringify({p:-27, q:16, r:-13.5, s:2.5, t:-16, u:5})
|| null.bug;
})();
(function () {
const f = ct( arr => {
var ret = [];
ct.afor( i, arr ).ct
{
ret.push( i, arr[ i ] );
}
return ret;
} );
f( [ 1, 20, 300, 4000 ] ).join( ',' )
=== [0,1,1,20,2,300,3,4000].join( ',' )
|| null.bug;
})();
(function () {
const sum = ct( arr => {
var sum = 0;
ct.afor( i, arr ).ct
{
sum += arr[i];
}
return sum;
} );
sum( [ 1, 20, 300, 4000 ] ) === 4321 || null.bug;
})();
(function () {
const f = ct( arr => {
var ret = 0;
ct.afor( i, arr ).ct
ret += i * arr[i];
return ret;
} );
f( [ 1, 20, 300, 4000 ] ) === 12620 || null.bug;
})();
(function () {
const f = ct( arr => {
var ret = 0;
ct.arof( i, arr ).ct
{
ret += i * arr[i];
}
return ret;
} );
f( [ 1, 20, 300, 4000 ] ) === 12620 || null.bug;
})();
(function () {
const f = ct( arr => {
var ret = [];
ct.arof( i, arr ).ct
{
ret.push( i, arr[i] );
}
return ret;
} );
f( [ 1, 20, 300, 4000 ] ).join(',')
=== [3,4000,2,300,1,20,0,1].join(',')
|| null.bug;
})();
(function () {
// see also: ct.at
const h = ct( arr => ct.last( arr ).ct + 3.45 );
h( [ 10.0, 20.0, 30.0, 40.0 ] ) === 43.45 || null.bug;
})();
(function () {
// Concise object definition
var f = ct( (o,a,b,c) => {
var d = a*3+b-2
, e = Math.sin( d*d-36 )
;
return ct.obj( {a,b,c,d,e,q : d-e, some_long_one : o.$} ).ct;
});
console.log( ''+f );
/* js console output:
((o,a,b,c) => {
var d = a*3+b-2
, e = Math.sin( d*d-36 )
;
return {a : a
, b : b
, c : c
, d : d
, e : e
, q : d-e
, some_long_one : o. some_long_one};
})
*/
JSON.stringify( f( { some_long_one : 12345 }, 1.0, 20.0, 300.0 ) )
=== `{"a":1,"b":20,"c":300,"d":21,"e":0.26234576530777837`
+`,"q":20.737654234692222,"some_long_one":12345}`
|| null.bug;
})();
ct(function () {
// Object destructuring as expression.
var a;
var q,c,r;
//...
a = {b:1,c:2,d:{e:'fgh'}}
,(ct.ode( {b:q,c,d:r} = a).ct)
,JSON.stringify([q,c,r])===JSON.stringify([1,2,{e:'fgh'}]) || null.bug;
})();
ct(function () {
// Object destructuring as `var` declaration statement.
var a = {b:1,c:2,d:{e:'fgh'}};
ct.odev( {b:q,c,d:r} = a ).ct;
JSON.stringify([q,c,r])===JSON.stringify([1,2,{e:'fgh'}]) || null.bug;
})();
(function () {
var f = ct( (o) => {
var ret = [];
ct.ofor( k, o ).ct
{
ret.push( [ k, o[ k ] ] );
}
ret.sort( (a,b) => a[0] < b[0] ? -1
: a[0] > b[0] ? +1
: 0 );
return ret;
});
var o0 = {a : 1, b : 2, c : 3}
, o = Object.create( o0 )
;
o.d = 4; o.e = 5; o.f = 6;
JSON.stringify( f( o ) )
=== '[["a",1],["b",2],["c",3],["d",4],["e",5],["f",6]]'
|| null.bug;
})();
(function () {
// ?. optional chaining operator
const f = ct( (o) => ct.opt( o.a.b.c ).ct || null );
console.log( ''+f );
/* js console output:
((o) => o
&& ct._tmp = o.a)
&& ct._tmp = ct._tmp.b)
&& ct._tmp.c ) || null)
*/
console.log( f( {} ) ); // js console output: null
console.log( f( {a:{b:{}}} ) ) // js console output: null
console.log( f( {a:{b:{c:123456}}} ) ) // js console output: 123456
f({}) === null || null.bug;
f({a:{b:{}}}) === null || null.bug;
f( {a:{b:{c:123456}}} ) === 123456 || null.bug;
})();
(function () {
// ?. optional chaining operator (explicit variant that should
// make removing ct.js easier in the future).
const f = ct( (o) => ct.opt( "o?.a?.b?.c" ).ct || null );
console.log( ''+f );
/* js console output:
((o) => o
&& ct._tmp = o.a)
&& ct._tmp = ct._tmp.b)
&& ct._tmp.c ) || null)
*/
console.log( f( {} ) ); // js console output: null
console.log( f( {a:{b:{}}} ) ) // js console output: null
console.log( f( {a:{b:{c:123456}}} ) ) // js console output: 123456
f({}) === null || null.bug;
f({a:{b:{}}}) === null || null.bug;
f( {a:{b:{c:123456}}} ) === 123456 || null.bug;
})();
(function () {
// ?. optional chaining operator (explicit variant that should
// make removing ct.js easier in the future).
const f = ct( (o) => ct.opt( 'o?.a?.b?.c' ).ct || null );
console.log( ''+f );
/* js console output:
((o) => o
&& ct._tmp = o.a)
&& ct._tmp = ct._tmp.b)
&& ct._tmp.c ) || null)
*/
console.log( f( {} ) ); // js console output: null
console.log( f( {a:{b:{}}} ) ) // js console output: null
console.log( f( {a:{b:{c:123456}}} ) ) // js console output: 123456
f({}) === null || null.bug;
f({a:{b:{}}}) === null || null.bug;
f( {a:{b:{c:123456}}} ) === 123456 || null.bug;
})();
(function () {
// ?. optional chaining operator (extended)
const f = ct( (o) => ct.opt( o[1].b["?"].d ).ct || null );
console.log( ''+f );
/* js console output:
((o) => o
&& ct._tmp = o[1])
&& ct._tmp = ct._tmp.b)
&& ct._tmp = ct._tmp["?"])
&& ct._tmp.d ) || null)
*/
console.log( f( [] ) ); // js console output: null
console.log( f( [0,{b:{}}] ) ) // js console output: null
console.log( f( [0,{b:{"?":{d:789}}}] ) ) // js console output: 789
f([]) === null || null.bug;
f( [0,{b:{}}] ) === null || null.bug;
f( [0,{b:{"?":{d:789}}}] ) === 789 || null.bug;
})();
(function () {
// Require an object
const f = ct( (o) => ct.oreq( o.a.b.c.d ).ct );
console.log( ''+f );
/* js console output:
((o) => ( o || ( o = {})
, ct._tmp = o.a || ( o.a = {}))
, ct._tmp = ct._tmp.b || ct._tmp.b = {}))
, ct._tmp = ct._tmp.c || ct._tmp.c = {}))
, ct._tmp.d || ct._tmp.d = {})) ))
*/
var o = {}
, d = f( o )
;
JSON.stringify( o ) === `{"a":{"b":{"c":{"d":{}}}}}` || null.bug;
JSON.stringify( d ) === `{}` || null.bug;
d === o.a.b.c.d || null.bug;
})();
(function () {
// Require an object
const f = ct( (o) => ct.oreq( o[1].b["?"].d ).ct );
console.log( ''+f );
/* js console output:
((o) => ( o || ( o = {})
, ct._tmp = o[1] || ( o[1] = {}))
, ct._tmp = ct._tmp.b || ct._tmp.b = {}))
, ct._tmp = ct._tmp["?"] || ct._tmp["?"] = {}))
, ct._tmp.d || ct._tmp.d = {})) ))
*/
var a = []
, d = f( a )
;
JSON.stringify( a ) === `[null,{"b":{"?":{"d":{}}}}]` || null.bug;
JSON.stringify( d ) === `{}` || null.bug;
d === a[1].b["?"].d || null.bug;
})();
ct(function () {
var x = 1, o = { y : { z : 2 } };
var s = ct.tli( 'x has the value ${x} and z*3.45 has the value ${o.y.z*3.45}' ).ct;
s === 'x has the value 1 and z*3.45 has the value 6.9'
|| null.bug;
})();