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PatternUtils.js
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PatternUtils.js
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import invariant from 'invariant'
function escapeRegExp(string) {
return string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')
}
function _compilePattern(pattern) {
let regexpSource = ''
const paramNames = []
const tokens = []
let match, lastIndex = 0, matcher = /:([a-zA-Z_$][a-zA-Z0-9_$]*)|\*\*|\*|\(|\)/g
while ((match = matcher.exec(pattern))) {
if (match.index !== lastIndex) {
tokens.push(pattern.slice(lastIndex, match.index))
regexpSource += escapeRegExp(pattern.slice(lastIndex, match.index))
}
if (match[1]) {
regexpSource += '([^/]+)'
paramNames.push(match[1])
} else if (match[0] === '**') {
regexpSource += '(.*)'
paramNames.push('splat')
} else if (match[0] === '*') {
regexpSource += '(.*?)'
paramNames.push('splat')
} else if (match[0] === '(') {
regexpSource += '(?:'
} else if (match[0] === ')') {
regexpSource += ')?'
}
tokens.push(match[0])
lastIndex = matcher.lastIndex
}
if (lastIndex !== pattern.length) {
tokens.push(pattern.slice(lastIndex, pattern.length))
regexpSource += escapeRegExp(pattern.slice(lastIndex, pattern.length))
}
return {
pattern,
regexpSource,
paramNames,
tokens
}
}
const CompiledPatternsCache = Object.create(null)
export function compilePattern(pattern) {
if (!CompiledPatternsCache[pattern])
CompiledPatternsCache[pattern] = _compilePattern(pattern)
return CompiledPatternsCache[pattern]
}
/**
* Attempts to match a pattern on the given pathname. Patterns may use
* the following special characters:
*
* - :paramName Matches a URL segment up to the next /, ?, or #. The
* captured string is considered a "param"
* - () Wraps a segment of the URL that is optional
* - * Consumes (non-greedy) all characters up to the next
* character in the pattern, or to the end of the URL if
* there is none
* - ** Consumes (greedy) all characters up to the next character
* in the pattern, or to the end of the URL if there is none
*
* The function calls callback(error, matched) when finished.
* The return value is an object with the following properties:
*
* - remainingPathname
* - paramNames
* - paramValues
*/
export function matchPattern(pattern, pathname) {
// Ensure pattern starts with leading slash for consistency with pathname.
if (pattern.charAt(0) !== '/') {
pattern = `/${pattern}`
}
let { regexpSource, paramNames, tokens } = compilePattern(pattern)
if (pattern.charAt(pattern.length - 1) !== '/') {
regexpSource += '/?' // Allow optional path separator at end.
}
// Special-case patterns like '*' for catch-all routes.
if (tokens[tokens.length - 1] === '*') {
regexpSource += '$'
}
const match = pathname.match(new RegExp(`^${regexpSource}`, 'i'))
if (match == null) {
return null
}
const matchedPath = match[0]
let remainingPathname = pathname.substr(matchedPath.length)
if (remainingPathname) {
// Require that the match ends at a path separator, if we didn't match
// the full path, so any remaining pathname is a new path segment.
if (matchedPath.charAt(matchedPath.length - 1) !== '/') {
return null
}
// If there is a remaining pathname, treat the path separator as part of
// the remaining pathname for properly continuing the match.
remainingPathname = `/${remainingPathname}`
}
return {
remainingPathname,
paramNames,
paramValues: match.slice(1).map(v => v && decodeURIComponent(v))
}
}
export function getParamNames(pattern) {
return compilePattern(pattern).paramNames
}
export function getParams(pattern, pathname) {
const match = matchPattern(pattern, pathname)
if (!match) {
return null
}
const { paramNames, paramValues } = match
const params = {}
paramNames.forEach((paramName, index) => {
params[paramName] = paramValues[index]
})
return params
}
/**
* Returns a version of the given pattern with params interpolated. Throws
* if there is a dynamic segment of the pattern for which there is no param.
*/
export function formatPattern(pattern, params) {
params = params || {}
const { tokens } = compilePattern(pattern)
let parenCount = 0, pathname = '', splatIndex = 0, parenHistory = []
let token, paramName, paramValue
for (let i = 0, len = tokens.length; i < len; ++i) {
token = tokens[i]
if (token === '*' || token === '**') {
paramValue = Array.isArray(params.splat) ? params.splat[splatIndex++] : params.splat
invariant(
paramValue != null || parenCount > 0,
'Missing splat #%s for path "%s"',
splatIndex, pattern
)
if (paramValue != null)
pathname += encodeURI(paramValue)
} else if (token === '(') {
parenHistory[parenCount] = ''
parenCount += 1
} else if (token === ')') {
const parenText = parenHistory.pop()
parenCount -= 1
if (parenCount)
parenHistory[parenCount - 1] += parenText
else
pathname += parenText
} else if (token.charAt(0) === ':') {
paramName = token.substring(1)
paramValue = params[paramName]
invariant(
paramValue != null || parenCount > 0,
'Missing "%s" parameter for path "%s"',
paramName, pattern
)
if (paramValue == null) {
if (parenCount) {
parenHistory[parenCount - 1] = ''
const curTokenIdx = tokens.indexOf(token)
const tokensSubset = tokens.slice(curTokenIdx, tokens.length)
let nextParenIdx = -1
for (let i = 0; i < tokensSubset.length; i++) {
if (tokensSubset[i] == ')') {
nextParenIdx = i
break
}
}
invariant(
nextParenIdx > 0,
'Path "%s" is missing end paren at segment "%s"', pattern, tokensSubset.join('')
)
// jump to ending paren
i = curTokenIdx + nextParenIdx - 1
}
}
else if (parenCount)
parenHistory[parenCount - 1] += encodeURIComponent(paramValue)
else
pathname += encodeURIComponent(paramValue)
} else {
if (parenCount)
parenHistory[parenCount - 1] += token
else
pathname += token
}
}
invariant(
parenCount <= 0,
'Path "%s" is missing end paren', pattern
)
return pathname.replace(/\/+/g, '/')
}