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// Limited implementation of python % string operator, supports only %s and %r for now
// (other formats are not used here, but may appear in custom templates)
'use strict'
const { inspect } = require('util')
module.exports = function sub(pattern, ...values) {
let regex = /%(?:(%)|(-)?(\*)?(?:\((\w+)\))?([A-Za-z]))/g
let result = pattern.replace(regex, function (_, is_literal, is_left_align, is_padded, name, format) {
if (is_literal) return '%'
let padded_count = 0
if (is_padded) {
if (values.length === 0) throw new TypeError('not enough arguments for format string')
padded_count = values.shift()
if (!Number.isInteger(padded_count)) throw new TypeError('* wants int')
}
let str
if (name !== undefined) {
let dict = values[0]
if (typeof dict !== 'object' || dict === null) throw new TypeError('format requires a mapping')
if (!(name in dict)) throw new TypeError(`no such key: '${name}'`)
str = dict[name]
} else {
if (values.length === 0) throw new TypeError('not enough arguments for format string')
str = values.shift()
}
switch (format) {
case 's':
str = String(str)
break
case 'r':
str = inspect(str)
break
case 'd':
case 'i':
if (typeof str !== 'number') {
throw new TypeError(`%${format} format: a number is required, not ${typeof str}`)
}
str = String(str.toFixed(0))
break
default:
throw new TypeError(`unsupported format character '${format}'`)
}
if (padded_count > 0) {
return is_left_align ? str.padEnd(padded_count) : str.padStart(padded_count)
} else {
return str
}
})
if (values.length) {
if (values.length === 1 && typeof values[0] === 'object' && values[0] !== null) {
// mapping
} else {
throw new TypeError('not all arguments converted during string formatting')
}
}
return result
}
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