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