Created
November 28, 2017 15:44
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function cartesian(arr) { | |
return arr.reduce((a, b) => | |
a.map(x => b.map(y => x.concat(y))) | |
.reduce((a, b) => a.concat(b), []), [[]]); | |
} | |
function parse(f){ | |
var re = /\[([0-9a-zA-Z,]+[^\]]+)\]/gm; | |
var m = null; | |
var res = []; | |
var lastIndex = 0; | |
while(m = re.exec(f)){ | |
res.push([f.substring(lastIndex, m.index)]); | |
res.push(m[1].split(",").map(i => "."+i)); | |
lastIndex = m.index + m[0].length; | |
} | |
return cartesian(res).map(r => r.join("")); | |
} | |
/** | |
* This makes part of a JSON2CSV engine | |
* The idea is to simplify the syntax to select fields from complex objects | |
* | |
* Given the document | |
*/ | |
var o = { a:{ | |
b:['val1'], | |
c:[{ | |
d:1, | |
e: 'val2', | |
f: 2.3 | |
}], | |
c1:[{ | |
d:1, | |
e: 'val2', | |
f: 2.3 | |
}] | |
} | |
} | |
parse("a[c,c1][0][e,f]").map(k => [k, eval("o." + k)]) | |
/* OUTPUT | |
(4) [Array(2), Array(2), Array(2), Array(2)] | |
0:(2) ["a.c[0].e", "val2"] | |
1:(2) ["a.c[0].f", 2.3] | |
2:(2) ["a.c1[0].e", "val2"] | |
3:(2) ["a.c1[0].f", 2.3] | |
*/ |
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