mirror of https://github.com/prometheus/prometheus
70 lines
2.2 KiB
Go
70 lines
2.2 KiB
Go
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package restful
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// Copyright 2013 Ernest Micklei. All rights reserved.
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// Use of this source code is governed by a license
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// that can be found in the LICENSE file.
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import (
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"bytes"
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"fmt"
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"regexp"
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"strings"
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)
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// PathExpression holds a compiled path expression (RegExp) needed to match against
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// Http request paths and to extract path parameter values.
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type pathExpression struct {
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LiteralCount int // the number of literal characters (means those not resulting from template variable substitution)
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VarCount int // the number of named parameters (enclosed by {}) in the path
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Matcher *regexp.Regexp
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Source string // Path as defined by the RouteBuilder
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tokens []string
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}
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// NewPathExpression creates a PathExpression from the input URL path.
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// Returns an error if the path is invalid.
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func newPathExpression(path string) (*pathExpression, error) {
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expression, literalCount, varCount, tokens := templateToRegularExpression(path)
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compiled, err := regexp.Compile(expression)
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if err != nil {
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return nil, err
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}
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return &pathExpression{literalCount, varCount, compiled, expression, tokens}, nil
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}
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// http://jsr311.java.net/nonav/releases/1.1/spec/spec3.html#x3-370003.7.3
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func templateToRegularExpression(template string) (expression string, literalCount int, varCount int, tokens []string) {
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var buffer bytes.Buffer
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buffer.WriteString("^")
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//tokens = strings.Split(template, "/")
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tokens = tokenizePath(template)
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for _, each := range tokens {
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if each == "" {
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continue
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}
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buffer.WriteString("/")
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if strings.HasPrefix(each, "{") {
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// check for regular expression in variable
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colon := strings.Index(each, ":")
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if colon != -1 {
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// extract expression
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paramExpr := strings.TrimSpace(each[colon+1 : len(each)-1])
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if paramExpr == "*" { // special case
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buffer.WriteString("(.*)")
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} else {
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buffer.WriteString(fmt.Sprintf("(%s)", paramExpr)) // between colon and closing moustache
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}
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} else {
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// plain var
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buffer.WriteString("([^/]+?)")
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}
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varCount += 1
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} else {
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literalCount += len(each)
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encoded := each // TODO URI encode
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buffer.WriteString(regexp.QuoteMeta(encoded))
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}
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}
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return strings.TrimRight(buffer.String(), "/") + "(/.*)?$", literalCount, varCount, tokens
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}
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