Public
Edited
Mar 8, 2020
Importers
1 star
readEx = regex => str => {
const match = str.match(new RegExp(regex))
if (!match) return {error: true, expecting: regex}
const rest = str.substr(match[0].length)
return {error: false, read: [match[0]], rest}
}
readVar = readEx(`^${IDENTIFIER}`)
readOp = readEx(`^ ?${OP} ?`)
readBool = readEx(`^ (and|or) `)
compose2 = (f, g) => str => {
let a = f(str)
if (a.error) return a
let b = g(a.rest)
if (b.error) return {after: a, ...b}
return {error: false, read: [...a.read, ...b.read], rest: b.rest}
}
compose = (...fs) => fs.reduce(compose2)
readRelation = str => {
const res = compose(readVar, readOp, readVar)(str)
if (res.error) return res
return {...res, read: [res.read]}
}
readRelation('x.top = 10').read
interleave = (sepBy, terms) => str => {
const firstRead = terms(str)
if (firstRead.error) return firstRead
let rest = firstRead.rest
let read = firstRead.read
while(rest !== '') {
const a = sepBy(rest)
if (a.error) return {error: false, read: read, rest}
const b = terms(a.rest)
if (b.error) return b
rest = b.rest
read = [...read, ...a.read, ...b.read]
}
return {error: false, read, rest}
}
readRelations = interleave(readBool, readRelation)
readRelations('a.time = 1 and b.user = 2').read
dropChar = c => str => {
if (str[0] !== c) return {error: true, expecting: c}
return {error: false, read: [], rest: str.substr(1)}
}
readGroups = {
const readGroup = str => {
const res = compose(dropChar('('), readRelations, dropChar(')'))(str)
if (res.error) return res
return {...res, read: [res.read]}
}
return interleave(readBool, readGroup)
}
readGroups('(a.time = 1 and b.user = 2) and (b.user = 3)').read
readGroups(exampleStr).read
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