mirror of
https://github.com/miniflux/v2.git
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174 lines
3.9 KiB
Go
174 lines
3.9 KiB
Go
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package webdav
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// The If header is covered by Section 10.4.
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// http://www.webdav.org/specs/rfc4918.html#HEADER_If
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import (
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"strings"
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)
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// ifHeader is a disjunction (OR) of ifLists.
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type ifHeader struct {
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lists []ifList
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}
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// ifList is a conjunction (AND) of Conditions, and an optional resource tag.
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type ifList struct {
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resourceTag string
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conditions []Condition
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}
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// parseIfHeader parses the "If: foo bar" HTTP header. The httpHeader string
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// should omit the "If:" prefix and have any "\r\n"s collapsed to a " ", as is
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// returned by req.Header.Get("If") for a http.Request req.
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func parseIfHeader(httpHeader string) (h ifHeader, ok bool) {
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s := strings.TrimSpace(httpHeader)
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switch tokenType, _, _ := lex(s); tokenType {
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case '(':
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return parseNoTagLists(s)
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case angleTokenType:
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return parseTaggedLists(s)
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default:
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return ifHeader{}, false
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}
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}
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func parseNoTagLists(s string) (h ifHeader, ok bool) {
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for {
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l, remaining, ok := parseList(s)
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if !ok {
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return ifHeader{}, false
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}
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h.lists = append(h.lists, l)
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if remaining == "" {
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return h, true
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}
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s = remaining
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}
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}
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func parseTaggedLists(s string) (h ifHeader, ok bool) {
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resourceTag, n := "", 0
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for first := true; ; first = false {
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tokenType, tokenStr, remaining := lex(s)
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switch tokenType {
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case angleTokenType:
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if !first && n == 0 {
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return ifHeader{}, false
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}
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resourceTag, n = tokenStr, 0
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s = remaining
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case '(':
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n++
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l, remaining, ok := parseList(s)
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if !ok {
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return ifHeader{}, false
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}
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l.resourceTag = resourceTag
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h.lists = append(h.lists, l)
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if remaining == "" {
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return h, true
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}
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s = remaining
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default:
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return ifHeader{}, false
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}
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}
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}
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func parseList(s string) (l ifList, remaining string, ok bool) {
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tokenType, _, s := lex(s)
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if tokenType != '(' {
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return ifList{}, "", false
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}
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for {
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tokenType, _, remaining = lex(s)
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if tokenType == ')' {
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if len(l.conditions) == 0 {
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return ifList{}, "", false
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}
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return l, remaining, true
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}
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c, remaining, ok := parseCondition(s)
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if !ok {
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return ifList{}, "", false
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}
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l.conditions = append(l.conditions, c)
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s = remaining
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}
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}
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func parseCondition(s string) (c Condition, remaining string, ok bool) {
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tokenType, tokenStr, s := lex(s)
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if tokenType == notTokenType {
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c.Not = true
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tokenType, tokenStr, s = lex(s)
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}
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switch tokenType {
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case strTokenType, angleTokenType:
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c.Token = tokenStr
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case squareTokenType:
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c.ETag = tokenStr
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default:
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return Condition{}, "", false
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}
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return c, s, true
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}
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// Single-rune tokens like '(' or ')' have a token type equal to their rune.
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// All other tokens have a negative token type.
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const (
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errTokenType = rune(-1)
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eofTokenType = rune(-2)
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strTokenType = rune(-3)
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notTokenType = rune(-4)
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angleTokenType = rune(-5)
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squareTokenType = rune(-6)
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)
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func lex(s string) (tokenType rune, tokenStr string, remaining string) {
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// The net/textproto Reader that parses the HTTP header will collapse
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// Linear White Space that spans multiple "\r\n" lines to a single " ",
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// so we don't need to look for '\r' or '\n'.
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for len(s) > 0 && (s[0] == '\t' || s[0] == ' ') {
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s = s[1:]
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}
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if len(s) == 0 {
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return eofTokenType, "", ""
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}
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i := 0
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loop:
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for ; i < len(s); i++ {
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switch s[i] {
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case '\t', ' ', '(', ')', '<', '>', '[', ']':
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break loop
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}
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}
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if i != 0 {
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tokenStr, remaining = s[:i], s[i:]
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if tokenStr == "Not" {
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return notTokenType, "", remaining
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}
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return strTokenType, tokenStr, remaining
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}
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j := 0
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switch s[0] {
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case '<':
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j, tokenType = strings.IndexByte(s, '>'), angleTokenType
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case '[':
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j, tokenType = strings.IndexByte(s, ']'), squareTokenType
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default:
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return rune(s[0]), "", s[1:]
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}
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if j < 0 {
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return errTokenType, "", ""
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}
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return tokenType, s[1:j], s[j+1:]
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}
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