Files
liquidjs/src/render/syntax.ts
T

101 lines
3.2 KiB
TypeScript

import * as lexical from '../parser/lexical'
import assert from '../util/assert'
import Context from '../context/context'
import { range, last, isFunction, toValue } from '../util/underscore'
import { isComparable } from '../drop/icomparable'
import { NullDrop } from '../drop/null-drop'
import { EmptyDrop } from '../drop/empty-drop'
import { BlankDrop } from '../drop/blank-drop'
const binaryOperators: {[key: string]: (lhs: any, rhs: any) => boolean} = {
'==': (l: any, r: any) => {
if (isComparable(l)) return l.equals(r)
if (isComparable(r)) return r.equals(l)
return l === r
},
'!=': (l: any, r: any) => {
if (isComparable(l)) return !l.equals(r)
if (isComparable(r)) return !r.equals(l)
return l !== r
},
'>': (l: any, r: any) => {
if (isComparable(l)) return l.gt(r)
if (isComparable(r)) return r.lt(l)
return l > r
},
'<': (l: any, r: any) => {
if (isComparable(l)) return l.lt(r)
if (isComparable(r)) return r.gt(l)
return l < r
},
'>=': (l: any, r: any) => {
if (isComparable(l)) return l.geq(r)
if (isComparable(r)) return r.leq(l)
return l >= r
},
'<=': (l: any, r: any) => {
if (isComparable(l)) return l.leq(r)
if (isComparable(r)) return r.geq(l)
return l <= r
},
'contains': (l: any, r: any) => {
return l && isFunction(l.indexOf) ? l.indexOf(r) > -1 : false
},
'and': (l: any, r: any) => isTruthy(l) && isTruthy(r),
'or': (l: any, r: any) => isTruthy(l) || isTruthy(r)
}
export async function parseExp (exp: string, ctx: Context): Promise<any> {
assert(ctx, 'unable to parseExp: scope undefined')
const operatorREs = lexical.operators
let match
for (let i = 0; i < operatorREs.length; i++) {
const operatorRE = operatorREs[i]
const expRE = new RegExp(`^(${lexical.quoteBalanced.source})(${operatorRE.source})(${lexical.quoteBalanced.source})$`)
if ((match = exp.match(expRE))) {
const l = await parseExp(match[1], ctx)
const op = binaryOperators[match[2].trim()]
const r = await parseExp(match[3], ctx)
return op(l, r)
}
}
if ((match = exp.match(lexical.rangeLine))) {
const low = await evalValue(match[1], ctx)
const high = await evalValue(match[2], ctx)
return range(+low, +high + 1)
}
return parseValue(exp, ctx)
}
export async function evalExp (str: string, ctx: Context): Promise<any> {
return toValue(await parseExp(str, ctx))
}
export async function parseValue (str: string | undefined, ctx: Context): Promise<any> {
if (!str) return null
str = str.trim()
if (str === 'true') return true
if (str === 'false') return false
if (str === 'nil' || str === 'null') return new NullDrop()
if (str === 'empty') return new EmptyDrop()
if (str === 'blank') return new BlankDrop()
if (!isNaN(Number(str))) return Number(str)
if ((str[0] === '"' || str[0] === "'") && str[0] === last(str)) return str.slice(1, -1)
return ctx.get(str)
}
export async function evalValue (str: string | undefined, ctx: Context) {
return toValue(await parseValue(str, ctx))
}
export function isTruthy (val: any): boolean {
return !isFalsy(val)
}
export function isFalsy (val: any): boolean {
return val === false || undefined === val || val === null
}