e81ccc406b
Change all license headers to comply with REUSE specification. Fix #16132 Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github> Co-authored-by: John Olheiser <john.olheiser@gmail.com>
93 lines
2.5 KiB
Go
93 lines
2.5 KiB
Go
// Copyright 2022 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package vars
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import (
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"fmt"
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"strings"
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"unicode"
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"unicode/utf8"
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)
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// ErrWrongSyntax represents a wrong syntax with a template
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type ErrWrongSyntax struct {
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Template string
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}
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func (err ErrWrongSyntax) Error() string {
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return fmt.Sprintf("wrong syntax found in %s", err.Template)
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}
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// ErrVarMissing represents an error that no matched variable
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type ErrVarMissing struct {
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Template string
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Var string
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}
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func (err ErrVarMissing) Error() string {
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return fmt.Sprintf("the variable %s is missing for %s", err.Var, err.Template)
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}
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// Expand replaces all variables like {var} by `vars` map, it always returns the expanded string regardless of errors
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// if error occurs, the error part doesn't change and is returned as it is.
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func Expand(template string, vars map[string]string) (string, error) {
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// in the future, if necessary, we can introduce some escape-char,
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// for example: it will use `#' as a reversed char, templates will use `{#{}` to do escape and output char '{'.
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var buf strings.Builder
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var err error
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posBegin := 0
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strLen := len(template)
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for posBegin < strLen {
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// find the next `{`
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pos := strings.IndexByte(template[posBegin:], '{')
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if pos == -1 {
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buf.WriteString(template[posBegin:])
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break
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}
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// copy texts between vars
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buf.WriteString(template[posBegin : posBegin+pos])
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// find the var between `{` and `}`/end
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posBegin += pos
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posEnd := posBegin + 1
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for posEnd < strLen {
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if template[posEnd] == '}' {
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posEnd++
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break
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} // in the future, if we need to support escape chars, we can do: if (isEscapeChar) { posEnd+=2 }
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posEnd++
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}
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// the var part, it can be "{", "{}", "{..." or or "{...}"
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part := template[posBegin:posEnd]
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posBegin = posEnd
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if part == "{}" || part[len(part)-1] != '}' {
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// treat "{}" or "{..." as error
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err = ErrWrongSyntax{Template: template}
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buf.WriteString(part)
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} else {
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// now we get a valid key "{...}"
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key := part[1 : len(part)-1]
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keyFirst, _ := utf8.DecodeRuneInString(key)
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if unicode.IsSpace(keyFirst) || unicode.IsPunct(keyFirst) || unicode.IsControl(keyFirst) {
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// the if key doesn't start with a letter, then we do not treat it as a var now
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buf.WriteString(part)
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} else {
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// look up in the map
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if val, ok := vars[key]; ok {
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buf.WriteString(val)
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} else {
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// write the non-existing var as it is
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buf.WriteString(part)
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err = ErrVarMissing{Template: template, Var: key}
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}
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}
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}
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}
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return buf.String(), err
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}
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