Initial Bitbucket→GitHub migration commit, based on release v2.0.0.

internal/twee2compat/twee2compat.go

@@ -0,0 +1,40 @@
+/*
+	Copyright © 2014–2019 Thomas Michael Edwards. All rights reserved.
+	Use of this source code is governed by a Simplified BSD License which
+	can be found in the LICENSE file.
+*/
+
+package twee2compat
+
+import (
+	"regexp"
+)
+
+// Twee2 line regexp: `^:: *([^\[]*?) *(\[(.*?)\])? *(<(.*?)>)? *$`
+// See: https://github.com/Dan-Q/twee2/blob/d7659d84b5415d594dcc868628d74c3c9b48f496/lib/twee2/story_file.rb#L61
+
+var (
+	twee2DetectRe *regexp.Regexp
+	twee2HeaderRe *regexp.Regexp
+	twee2BadPosRe *regexp.Regexp
+)
+
+func hasTwee2Syntax(s []byte) bool {
+	// Initialize and cache the regular expressions if necessary.
+	if twee2DetectRe == nil {
+		twee2DetectRe = regexp.MustCompile(`(?m)^:: *[^\[]*?(?: *\[.*?\])? *<(.*?)> *$`)
+		twee2HeaderRe = regexp.MustCompile(`(?m)^(:: *[^\[]*?)( *\[.*?\])?(?: *<(.*?)>)? *$`)
+		twee2BadPosRe = regexp.MustCompile(`(?m)^(::.*?) *{"position":" *"}$`)
+	}
+	return twee2DetectRe.Match(s)
+}
+
+// ToV3 returns a copy of the slice s with all instances of Twee2 position blocks
+// replaced with Twee v3 metadata blocks.
+func ToV3(s []byte) []byte {
+	if hasTwee2Syntax(s) {
+		s = twee2HeaderRe.ReplaceAll(s, []byte(`${1}${2} {"position":"${3}"}`))
+		s = twee2BadPosRe.ReplaceAll(s, []byte(`$1`))
+	}
+	return s
+}