add support for PathValue and SetPathValue from go v1.23.7 (#38)

* add support for PathValue and SetPathValue from go v1.23.7
* add TINYGO notice to pattern.go, proper copy paste of PathValue func

http/pattern.go

@@ -0,0 +1,208 @@
+// TINYGO: The following is copied and modified from Go 1.23.7 official implementation.
+
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Patterns for ServeMux routing.
+
+package http
+
+import (
+	"errors"
+	"fmt"
+	"net/url"
+	"strings"
+	"unicode"
+)
+
+// A pattern is something that can be matched against an HTTP request.
+// It has an optional method, an optional host, and a path.
+type pattern struct {
+	str    string // original string
+	method string
+	host   string
+	// The representation of a path differs from the surface syntax, which
+	// simplifies most algorithms.
+	//
+	// Paths ending in '/' are represented with an anonymous "..." wildcard.
+	// For example, the path "a/" is represented as a literal segment "a" followed
+	// by a segment with multi==true.
+	//
+	// Paths ending in "{$}" are represented with the literal segment "/".
+	// For example, the path "a/{$}" is represented as a literal segment "a" followed
+	// by a literal segment "/".
+	segments []segment
+	loc      string // source location of registering call, for helpful messages
+}
+
+func (p *pattern) String() string { return p.str }
+
+func (p *pattern) lastSegment() segment {
+	return p.segments[len(p.segments)-1]
+}
+
+// A segment is a pattern piece that matches one or more path segments, or
+// a trailing slash.
+//
+// If wild is false, it matches a literal segment, or, if s == "/", a trailing slash.
+// Examples:
+//
+//	"a" => segment{s: "a"}
+//	"/{$}" => segment{s: "/"}
+//
+// If wild is true and multi is false, it matches a single path segment.
+// Example:
+//
+//	"{x}" => segment{s: "x", wild: true}
+//
+// If both wild and multi are true, it matches all remaining path segments.
+// Example:
+//
+//	"{rest...}" => segment{s: "rest", wild: true, multi: true}
+type segment struct {
+	s     string // literal or wildcard name or "/" for "/{$}".
+	wild  bool
+	multi bool // "..." wildcard
+}
+
+// parsePattern parses a string into a Pattern.
+// The string's syntax is
+//
+//	[METHOD] [HOST]/[PATH]
+//
+// where:
+//   - METHOD is an HTTP method
+//   - HOST is a hostname
+//   - PATH consists of slash-separated segments, where each segment is either
+//     a literal or a wildcard of the form "{name}", "{name...}", or "{$}".
+//
+// METHOD, HOST and PATH are all optional; that is, the string can be "/".
+// If METHOD is present, it must be followed by at least one space or tab.
+// Wildcard names must be valid Go identifiers.
+// The "{$}" and "{name...}" wildcard must occur at the end of PATH.
+// PATH may end with a '/'.
+// Wildcard names in a path must be distinct.
+func parsePattern(s string) (_ *pattern, err error) {
+	if len(s) == 0 {
+		return nil, errors.New("empty pattern")
+	}
+	off := 0 // offset into string
+	defer func() {
+		if err != nil {
+			err = fmt.Errorf("at offset %d: %w", off, err)
+		}
+	}()
+
+	method, rest, found := s, "", false
+	if i := strings.IndexAny(s, " \t"); i >= 0 {
+		method, rest, found = s[:i], strings.TrimLeft(s[i+1:], " \t"), true
+	}
+	if !found {
+		rest = method
+		method = ""
+	}
+	if method != "" && !validMethod(method) {
+		return nil, fmt.Errorf("invalid method %q", method)
+	}
+	p := &pattern{str: s, method: method}
+
+	if found {
+		off = len(method) + 1
+	}
+	i := strings.IndexByte(rest, '/')
+	if i < 0 {
+		return nil, errors.New("host/path missing /")
+	}
+	p.host = rest[:i]
+	rest = rest[i:]
+	if j := strings.IndexByte(p.host, '{'); j >= 0 {
+		off += j
+		return nil, errors.New("host contains '{' (missing initial '/'?)")
+	}
+	// At this point, rest is the path.
+	off += i
+
+	// An unclean path with a method that is not CONNECT can never match,
+	// because paths are cleaned before matching.
+	if method != "" && method != "CONNECT" && rest != cleanPath(rest) {
+		return nil, errors.New("non-CONNECT pattern with unclean path can never match")
+	}
+
+	seenNames := map[string]bool{} // remember wildcard names to catch dups
+	for len(rest) > 0 {
+		// Invariant: rest[0] == '/'.
+		rest = rest[1:]
+		off = len(s) - len(rest)
+		if len(rest) == 0 {
+			// Trailing slash.
+			p.segments = append(p.segments, segment{wild: true, multi: true})
+			break
+		}
+		i := strings.IndexByte(rest, '/')
+		if i < 0 {
+			i = len(rest)
+		}
+		var seg string
+		seg, rest = rest[:i], rest[i:]
+		if i := strings.IndexByte(seg, '{'); i < 0 {
+			// Literal.
+			seg = pathUnescape(seg)
+			p.segments = append(p.segments, segment{s: seg})
+		} else {
+			// Wildcard.
+			if i != 0 {
+				return nil, errors.New("bad wildcard segment (must start with '{')")
+			}
+			if seg[len(seg)-1] != '}' {
+				return nil, errors.New("bad wildcard segment (must end with '}')")
+			}
+			name := seg[1 : len(seg)-1]
+			if name == "$" {
+				if len(rest) != 0 {
+					return nil, errors.New("{$} not at end")
+				}
+				p.segments = append(p.segments, segment{s: "/"})
+				break
+			}
+			name, multi := strings.CutSuffix(name, "...")
+			if multi && len(rest) != 0 {
+				return nil, errors.New("{...} wildcard not at end")
+			}
+			if name == "" {
+				return nil, errors.New("empty wildcard")
+			}
+			if !isValidWildcardName(name) {
+				return nil, fmt.Errorf("bad wildcard name %q", name)
+			}
+			if seenNames[name] {
+				return nil, fmt.Errorf("duplicate wildcard name %q", name)
+			}
+			seenNames[name] = true
+			p.segments = append(p.segments, segment{s: name, wild: true, multi: multi})
+		}
+	}
+	return p, nil
+}
+
+func isValidWildcardName(s string) bool {
+	if s == "" {
+		return false
+	}
+	// Valid Go identifier.
+	for i, c := range s {
+		if !unicode.IsLetter(c) && c != '_' && (i == 0 || !unicode.IsDigit(c)) {
+			return false
+		}
+	}
+	return true
+}
+
+func pathUnescape(path string) string {
+	u, err := url.PathUnescape(path)
+	if err != nil {
+		// Invalidly escaped path; use the original
+		return path
+	}
+	return u
+}