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-rw-r--r--modules/git/foreachref/format.go83
1 files changed, 83 insertions, 0 deletions
diff --git a/modules/git/foreachref/format.go b/modules/git/foreachref/format.go
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+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package foreachref
+
+import (
+ "encoding/hex"
+ "fmt"
+ "io"
+ "strings"
+)
+
+var (
+ nullChar = []byte("\x00")
+ dualNullChar = []byte("\x00\x00")
+)
+
+// Format supports specifying and parsing an output format for 'git
+// for-each-ref'. See See git-for-each-ref(1) for available fields.
+type Format struct {
+ // fieldNames hold %(fieldname)s to be passed to the '--format' flag of
+ // for-each-ref. See git-for-each-ref(1) for available fields.
+ fieldNames []string
+
+ // fieldDelim is the character sequence that is used to separate fields
+ // for each reference. fieldDelim and refDelim should be selected to not
+ // interfere with each other and to not be present in field values.
+ fieldDelim []byte
+ // fieldDelimStr is a string representation of fieldDelim. Used to save
+ // us from repetitive reallocation whenever we need the delimiter as a
+ // string.
+ fieldDelimStr string
+ // refDelim is the character sequence used to separate reference from
+ // each other in the output. fieldDelim and refDelim should be selected
+ // to not interfere with each other and to not be present in field
+ // values.
+ refDelim []byte
+}
+
+// NewFormat creates a forEachRefFormat using the specified fieldNames. See
+// git-for-each-ref(1) for available fields.
+func NewFormat(fieldNames ...string) Format {
+ return Format{
+ fieldNames: fieldNames,
+ fieldDelim: nullChar,
+ fieldDelimStr: string(nullChar),
+ refDelim: dualNullChar,
+ }
+}
+
+// Flag returns a for-each-ref --format flag value that captures the fieldNames.
+func (f Format) Flag() string {
+ var formatFlag strings.Builder
+ for i, field := range f.fieldNames {
+ // field key and field value
+ formatFlag.WriteString(fmt.Sprintf("%s %%(%s)", field, field))
+
+ if i < len(f.fieldNames)-1 {
+ // note: escape delimiters to allow control characters as
+ // delimiters. For example, '%00' for null character or '%0a'
+ // for newline.
+ formatFlag.WriteString(f.hexEscaped(f.fieldDelim))
+ }
+ }
+ formatFlag.WriteString(f.hexEscaped(f.refDelim))
+ return formatFlag.String()
+}
+
+// Parser returns a Parser capable of parsing 'git for-each-ref' output produced
+// with this Format.
+func (f Format) Parser(r io.Reader) *Parser {
+ return NewParser(r, f)
+}
+
+// hexEscaped produces hex-escpaed characters from a string. For example, "\n\0"
+// would turn into "%0a%00".
+func (f Format) hexEscaped(delim []byte) string {
+ escaped := ""
+ for i := 0; i < len(delim); i++ {
+ escaped += "%" + hex.EncodeToString([]byte{delim[i]})
+ }
+ return escaped
+}