--- /dev/null
+// Copyright 2017 Frank Schroeder. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package properties
+
+// BUG(frank): Set() does not check for invalid unicode literals since this is currently handled by the lexer.
+// BUG(frank): Write() does not allow to configure the newline character. Therefore, on Windows LF is used.
+
+import (
+ "fmt"
+ "io"
+ "log"
+ "os"
+ "regexp"
+ "strconv"
+ "strings"
+ "time"
+ "unicode/utf8"
+)
+
+// ErrorHandlerFunc defines the type of function which handles failures
+// of the MustXXX() functions. An error handler function must exit
+// the application after handling the error.
+type ErrorHandlerFunc func(error)
+
+// ErrorHandler is the function which handles failures of the MustXXX()
+// functions. The default is LogFatalHandler.
+var ErrorHandler ErrorHandlerFunc = LogFatalHandler
+
+// LogHandlerFunc defines the function prototype for logging errors.
+type LogHandlerFunc func(fmt string, args ...interface{})
+
+// LogPrintf defines a log handler which uses log.Printf.
+var LogPrintf LogHandlerFunc = log.Printf
+
+// LogFatalHandler handles the error by logging a fatal error and exiting.
+func LogFatalHandler(err error) {
+ log.Fatal(err)
+}
+
+// PanicHandler handles the error by panicking.
+func PanicHandler(err error) {
+ panic(err)
+}
+
+// -----------------------------------------------------------------------------
+
+// A Properties contains the key/value pairs from the properties input.
+// All values are stored in unexpanded form and are expanded at runtime
+type Properties struct {
+ // Pre-/Postfix for property expansion.
+ Prefix string
+ Postfix string
+
+ // DisableExpansion controls the expansion of properties on Get()
+ // and the check for circular references on Set(). When set to
+ // true Properties behaves like a simple key/value store and does
+ // not check for circular references on Get() or on Set().
+ DisableExpansion bool
+
+ // Stores the key/value pairs
+ m map[string]string
+
+ // Stores the comments per key.
+ c map[string][]string
+
+ // Stores the keys in order of appearance.
+ k []string
+}
+
+// NewProperties creates a new Properties struct with the default
+// configuration for "${key}" expressions.
+func NewProperties() *Properties {
+ return &Properties{
+ Prefix: "${",
+ Postfix: "}",
+ m: map[string]string{},
+ c: map[string][]string{},
+ k: []string{},
+ }
+}
+
+// Get returns the expanded value for the given key if exists.
+// Otherwise, ok is false.
+func (p *Properties) Get(key string) (value string, ok bool) {
+ v, ok := p.m[key]
+ if p.DisableExpansion {
+ return v, ok
+ }
+ if !ok {
+ return "", false
+ }
+
+ expanded, err := p.expand(v)
+
+ // we guarantee that the expanded value is free of
+ // circular references and malformed expressions
+ // so we panic if we still get an error here.
+ if err != nil {
+ ErrorHandler(fmt.Errorf("%s in %q", err, key+" = "+v))
+ }
+
+ return expanded, true
+}
+
+// MustGet returns the expanded value for the given key if exists.
+// Otherwise, it panics.
+func (p *Properties) MustGet(key string) string {
+ if v, ok := p.Get(key); ok {
+ return v
+ }
+ ErrorHandler(invalidKeyError(key))
+ panic("ErrorHandler should exit")
+}
+
+// ----------------------------------------------------------------------------
+
+// ClearComments removes the comments for all keys.
+func (p *Properties) ClearComments() {
+ p.c = map[string][]string{}
+}
+
+// ----------------------------------------------------------------------------
+
+// GetComment returns the last comment before the given key or an empty string.
+func (p *Properties) GetComment(key string) string {
+ comments, ok := p.c[key]
+ if !ok || len(comments) == 0 {
+ return ""
+ }
+ return comments[len(comments)-1]
+}
+
+// ----------------------------------------------------------------------------
+
+// GetComments returns all comments that appeared before the given key or nil.
+func (p *Properties) GetComments(key string) []string {
+ if comments, ok := p.c[key]; ok {
+ return comments
+ }
+ return nil
+}
+
+// ----------------------------------------------------------------------------
+
+// SetComment sets the comment for the key.
+func (p *Properties) SetComment(key, comment string) {
+ p.c[key] = []string{comment}
+}
+
+// ----------------------------------------------------------------------------
+
+// SetComments sets the comments for the key. If the comments are nil then
+// all comments for this key are deleted.
+func (p *Properties) SetComments(key string, comments []string) {
+ if comments == nil {
+ delete(p.c, key)
+ return
+ }
+ p.c[key] = comments
+}
+
+// ----------------------------------------------------------------------------
+
+// GetBool checks if the expanded value is one of '1', 'yes',
+// 'true' or 'on' if the key exists. The comparison is case-insensitive.
+// If the key does not exist the default value is returned.
+func (p *Properties) GetBool(key string, def bool) bool {
+ v, err := p.getBool(key)
+ if err != nil {
+ return def
+ }
+ return v
+}
+
+// MustGetBool checks if the expanded value is one of '1', 'yes',
+// 'true' or 'on' if the key exists. The comparison is case-insensitive.
+// If the key does not exist the function panics.
+func (p *Properties) MustGetBool(key string) bool {
+ v, err := p.getBool(key)
+ if err != nil {
+ ErrorHandler(err)
+ }
+ return v
+}
+
+func (p *Properties) getBool(key string) (value bool, err error) {
+ if v, ok := p.Get(key); ok {
+ return boolVal(v), nil
+ }
+ return false, invalidKeyError(key)
+}
+
+func boolVal(v string) bool {
+ v = strings.ToLower(v)
+ return v == "1" || v == "true" || v == "yes" || v == "on"
+}
+
+// ----------------------------------------------------------------------------
+
+// GetDuration parses the expanded value as an time.Duration (in ns) if the
+// key exists. If key does not exist or the value cannot be parsed the default
+// value is returned. In almost all cases you want to use GetParsedDuration().
+func (p *Properties) GetDuration(key string, def time.Duration) time.Duration {
+ v, err := p.getInt64(key)
+ if err != nil {
+ return def
+ }
+ return time.Duration(v)
+}
+
+// MustGetDuration parses the expanded value as an time.Duration (in ns) if
+// the key exists. If key does not exist or the value cannot be parsed the
+// function panics. In almost all cases you want to use MustGetParsedDuration().
+func (p *Properties) MustGetDuration(key string) time.Duration {
+ v, err := p.getInt64(key)
+ if err != nil {
+ ErrorHandler(err)
+ }
+ return time.Duration(v)
+}
+
+// ----------------------------------------------------------------------------
+
+// GetParsedDuration parses the expanded value with time.ParseDuration() if the key exists.
+// If key does not exist or the value cannot be parsed the default
+// value is returned.
+func (p *Properties) GetParsedDuration(key string, def time.Duration) time.Duration {
+ s, ok := p.Get(key)
+ if !ok {
+ return def
+ }
+ v, err := time.ParseDuration(s)
+ if err != nil {
+ return def
+ }
+ return v
+}
+
+// MustGetParsedDuration parses the expanded value with time.ParseDuration() if the key exists.
+// If key does not exist or the value cannot be parsed the function panics.
+func (p *Properties) MustGetParsedDuration(key string) time.Duration {
+ s, ok := p.Get(key)
+ if !ok {
+ ErrorHandler(invalidKeyError(key))
+ }
+ v, err := time.ParseDuration(s)
+ if err != nil {
+ ErrorHandler(err)
+ }
+ return v
+}
+
+// ----------------------------------------------------------------------------
+
+// GetFloat64 parses the expanded value as a float64 if the key exists.
+// If key does not exist or the value cannot be parsed the default
+// value is returned.
+func (p *Properties) GetFloat64(key string, def float64) float64 {
+ v, err := p.getFloat64(key)
+ if err != nil {
+ return def
+ }
+ return v
+}
+
+// MustGetFloat64 parses the expanded value as a float64 if the key exists.
+// If key does not exist or the value cannot be parsed the function panics.
+func (p *Properties) MustGetFloat64(key string) float64 {
+ v, err := p.getFloat64(key)
+ if err != nil {
+ ErrorHandler(err)
+ }
+ return v
+}
+
+func (p *Properties) getFloat64(key string) (value float64, err error) {
+ if v, ok := p.Get(key); ok {
+ value, err = strconv.ParseFloat(v, 64)
+ if err != nil {
+ return 0, err
+ }
+ return value, nil
+ }
+ return 0, invalidKeyError(key)
+}
+
+// ----------------------------------------------------------------------------
+
+// GetInt parses the expanded value as an int if the key exists.
+// If key does not exist or the value cannot be parsed the default
+// value is returned. If the value does not fit into an int the
+// function panics with an out of range error.
+func (p *Properties) GetInt(key string, def int) int {
+ v, err := p.getInt64(key)
+ if err != nil {
+ return def
+ }
+ return intRangeCheck(key, v)
+}
+
+// MustGetInt parses the expanded value as an int if the key exists.
+// If key does not exist or the value cannot be parsed the function panics.
+// If the value does not fit into an int the function panics with
+// an out of range error.
+func (p *Properties) MustGetInt(key string) int {
+ v, err := p.getInt64(key)
+ if err != nil {
+ ErrorHandler(err)
+ }
+ return intRangeCheck(key, v)
+}
+
+// ----------------------------------------------------------------------------
+
+// GetInt64 parses the expanded value as an int64 if the key exists.
+// If key does not exist or the value cannot be parsed the default
+// value is returned.
+func (p *Properties) GetInt64(key string, def int64) int64 {
+ v, err := p.getInt64(key)
+ if err != nil {
+ return def
+ }
+ return v
+}
+
+// MustGetInt64 parses the expanded value as an int if the key exists.
+// If key does not exist or the value cannot be parsed the function panics.
+func (p *Properties) MustGetInt64(key string) int64 {
+ v, err := p.getInt64(key)
+ if err != nil {
+ ErrorHandler(err)
+ }
+ return v
+}
+
+func (p *Properties) getInt64(key string) (value int64, err error) {
+ if v, ok := p.Get(key); ok {
+ value, err = strconv.ParseInt(v, 10, 64)
+ if err != nil {
+ return 0, err
+ }
+ return value, nil
+ }
+ return 0, invalidKeyError(key)
+}
+
+// ----------------------------------------------------------------------------
+
+// GetUint parses the expanded value as an uint if the key exists.
+// If key does not exist or the value cannot be parsed the default
+// value is returned. If the value does not fit into an int the
+// function panics with an out of range error.
+func (p *Properties) GetUint(key string, def uint) uint {
+ v, err := p.getUint64(key)
+ if err != nil {
+ return def
+ }
+ return uintRangeCheck(key, v)
+}
+
+// MustGetUint parses the expanded value as an int if the key exists.
+// If key does not exist or the value cannot be parsed the function panics.
+// If the value does not fit into an int the function panics with
+// an out of range error.
+func (p *Properties) MustGetUint(key string) uint {
+ v, err := p.getUint64(key)
+ if err != nil {
+ ErrorHandler(err)
+ }
+ return uintRangeCheck(key, v)
+}
+
+// ----------------------------------------------------------------------------
+
+// GetUint64 parses the expanded value as an uint64 if the key exists.
+// If key does not exist or the value cannot be parsed the default
+// value is returned.
+func (p *Properties) GetUint64(key string, def uint64) uint64 {
+ v, err := p.getUint64(key)
+ if err != nil {
+ return def
+ }
+ return v
+}
+
+// MustGetUint64 parses the expanded value as an int if the key exists.
+// If key does not exist or the value cannot be parsed the function panics.
+func (p *Properties) MustGetUint64(key string) uint64 {
+ v, err := p.getUint64(key)
+ if err != nil {
+ ErrorHandler(err)
+ }
+ return v
+}
+
+func (p *Properties) getUint64(key string) (value uint64, err error) {
+ if v, ok := p.Get(key); ok {
+ value, err = strconv.ParseUint(v, 10, 64)
+ if err != nil {
+ return 0, err
+ }
+ return value, nil
+ }
+ return 0, invalidKeyError(key)
+}
+
+// ----------------------------------------------------------------------------
+
+// GetString returns the expanded value for the given key if exists or
+// the default value otherwise.
+func (p *Properties) GetString(key, def string) string {
+ if v, ok := p.Get(key); ok {
+ return v
+ }
+ return def
+}
+
+// MustGetString returns the expanded value for the given key if exists or
+// panics otherwise.
+func (p *Properties) MustGetString(key string) string {
+ if v, ok := p.Get(key); ok {
+ return v
+ }
+ ErrorHandler(invalidKeyError(key))
+ panic("ErrorHandler should exit")
+}
+
+// ----------------------------------------------------------------------------
+
+// Filter returns a new properties object which contains all properties
+// for which the key matches the pattern.
+func (p *Properties) Filter(pattern string) (*Properties, error) {
+ re, err := regexp.Compile(pattern)
+ if err != nil {
+ return nil, err
+ }
+
+ return p.FilterRegexp(re), nil
+}
+
+// FilterRegexp returns a new properties object which contains all properties
+// for which the key matches the regular expression.
+func (p *Properties) FilterRegexp(re *regexp.Regexp) *Properties {
+ pp := NewProperties()
+ for _, k := range p.k {
+ if re.MatchString(k) {
+ // TODO(fs): we are ignoring the error which flags a circular reference.
+ // TODO(fs): since we are just copying a subset of keys this cannot happen (fingers crossed)
+ pp.Set(k, p.m[k])
+ }
+ }
+ return pp
+}
+
+// FilterPrefix returns a new properties object with a subset of all keys
+// with the given prefix.
+func (p *Properties) FilterPrefix(prefix string) *Properties {
+ pp := NewProperties()
+ for _, k := range p.k {
+ if strings.HasPrefix(k, prefix) {
+ // TODO(fs): we are ignoring the error which flags a circular reference.
+ // TODO(fs): since we are just copying a subset of keys this cannot happen (fingers crossed)
+ pp.Set(k, p.m[k])
+ }
+ }
+ return pp
+}
+
+// FilterStripPrefix returns a new properties object with a subset of all keys
+// with the given prefix and the prefix removed from the keys.
+func (p *Properties) FilterStripPrefix(prefix string) *Properties {
+ pp := NewProperties()
+ n := len(prefix)
+ for _, k := range p.k {
+ if len(k) > len(prefix) && strings.HasPrefix(k, prefix) {
+ // TODO(fs): we are ignoring the error which flags a circular reference.
+ // TODO(fs): since we are modifying keys I am not entirely sure whether we can create a circular reference
+ // TODO(fs): this function should probably return an error but the signature is fixed
+ pp.Set(k[n:], p.m[k])
+ }
+ }
+ return pp
+}
+
+// Len returns the number of keys.
+func (p *Properties) Len() int {
+ return len(p.m)
+}
+
+// Keys returns all keys in the same order as in the input.
+func (p *Properties) Keys() []string {
+ keys := make([]string, len(p.k))
+ copy(keys, p.k)
+ return keys
+}
+
+// Set sets the property key to the corresponding value.
+// If a value for key existed before then ok is true and prev
+// contains the previous value. If the value contains a
+// circular reference or a malformed expression then
+// an error is returned.
+// An empty key is silently ignored.
+func (p *Properties) Set(key, value string) (prev string, ok bool, err error) {
+ if key == "" {
+ return "", false, nil
+ }
+
+ // if expansion is disabled we allow circular references
+ if p.DisableExpansion {
+ prev, ok = p.Get(key)
+ p.m[key] = value
+ if !ok {
+ p.k = append(p.k, key)
+ }
+ return prev, ok, nil
+ }
+
+ // to check for a circular reference we temporarily need
+ // to set the new value. If there is an error then revert
+ // to the previous state. Only if all tests are successful
+ // then we add the key to the p.k list.
+ prev, ok = p.Get(key)
+ p.m[key] = value
+
+ // now check for a circular reference
+ _, err = p.expand(value)
+ if err != nil {
+
+ // revert to the previous state
+ if ok {
+ p.m[key] = prev
+ } else {
+ delete(p.m, key)
+ }
+
+ return "", false, err
+ }
+
+ if !ok {
+ p.k = append(p.k, key)
+ }
+
+ return prev, ok, nil
+}
+
+// SetValue sets property key to the default string value
+// as defined by fmt.Sprintf("%v").
+func (p *Properties) SetValue(key string, value interface{}) error {
+ _, _, err := p.Set(key, fmt.Sprintf("%v", value))
+ return err
+}
+
+// MustSet sets the property key to the corresponding value.
+// If a value for key existed before then ok is true and prev
+// contains the previous value. An empty key is silently ignored.
+func (p *Properties) MustSet(key, value string) (prev string, ok bool) {
+ prev, ok, err := p.Set(key, value)
+ if err != nil {
+ ErrorHandler(err)
+ }
+ return prev, ok
+}
+
+// String returns a string of all expanded 'key = value' pairs.
+func (p *Properties) String() string {
+ var s string
+ for _, key := range p.k {
+ value, _ := p.Get(key)
+ s = fmt.Sprintf("%s%s = %s\n", s, key, value)
+ }
+ return s
+}
+
+// Write writes all unexpanded 'key = value' pairs to the given writer.
+// Write returns the number of bytes written and any write error encountered.
+func (p *Properties) Write(w io.Writer, enc Encoding) (n int, err error) {
+ return p.WriteComment(w, "", enc)
+}
+
+// WriteComment writes all unexpanced 'key = value' pairs to the given writer.
+// If prefix is not empty then comments are written with a blank line and the
+// given prefix. The prefix should be either "# " or "! " to be compatible with
+// the properties file format. Otherwise, the properties parser will not be
+// able to read the file back in. It returns the number of bytes written and
+// any write error encountered.
+func (p *Properties) WriteComment(w io.Writer, prefix string, enc Encoding) (n int, err error) {
+ var x int
+
+ for _, key := range p.k {
+ value := p.m[key]
+
+ if prefix != "" {
+ if comments, ok := p.c[key]; ok {
+ // don't print comments if they are all empty
+ allEmpty := true
+ for _, c := range comments {
+ if c != "" {
+ allEmpty = false
+ break
+ }
+ }
+
+ if !allEmpty {
+ // add a blank line between entries but not at the top
+ if len(comments) > 0 && n > 0 {
+ x, err = fmt.Fprintln(w)
+ if err != nil {
+ return
+ }
+ n += x
+ }
+
+ for _, c := range comments {
+ x, err = fmt.Fprintf(w, "%s%s\n", prefix, encode(c, "", enc))
+ if err != nil {
+ return
+ }
+ n += x
+ }
+ }
+ }
+ }
+
+ x, err = fmt.Fprintf(w, "%s = %s\n", encode(key, " :", enc), encode(value, "", enc))
+ if err != nil {
+ return
+ }
+ n += x
+ }
+ return
+}
+
+// Map returns a copy of the properties as a map.
+func (p *Properties) Map() map[string]string {
+ m := make(map[string]string)
+ for k, v := range p.m {
+ m[k] = v
+ }
+ return m
+}
+
+// FilterFunc returns a copy of the properties which includes the values which passed all filters.
+func (p *Properties) FilterFunc(filters ...func(k, v string) bool) *Properties {
+ pp := NewProperties()
+outer:
+ for k, v := range p.m {
+ for _, f := range filters {
+ if !f(k, v) {
+ continue outer
+ }
+ pp.Set(k, v)
+ }
+ }
+ return pp
+}
+
+// ----------------------------------------------------------------------------
+
+// Delete removes the key and its comments.
+func (p *Properties) Delete(key string) {
+ delete(p.m, key)
+ delete(p.c, key)
+ newKeys := []string{}
+ for _, k := range p.k {
+ if k != key {
+ newKeys = append(newKeys, k)
+ }
+ }
+ p.k = newKeys
+}
+
+// Merge merges properties, comments and keys from other *Properties into p
+func (p *Properties) Merge(other *Properties) {
+ for k, v := range other.m {
+ p.m[k] = v
+ }
+ for k, v := range other.c {
+ p.c[k] = v
+ }
+
+outer:
+ for _, otherKey := range other.k {
+ for _, key := range p.k {
+ if otherKey == key {
+ continue outer
+ }
+ }
+ p.k = append(p.k, otherKey)
+ }
+}
+
+// ----------------------------------------------------------------------------
+
+// check expands all values and returns an error if a circular reference or
+// a malformed expression was found.
+func (p *Properties) check() error {
+ for _, value := range p.m {
+ if _, err := p.expand(value); err != nil {
+ return err
+ }
+ }
+ return nil
+}
+
+func (p *Properties) expand(input string) (string, error) {
+ // no pre/postfix -> nothing to expand
+ if p.Prefix == "" && p.Postfix == "" {
+ return input, nil
+ }
+
+ return expand(input, make(map[string]bool), p.Prefix, p.Postfix, p.m)
+}
+
+// expand recursively expands expressions of '(prefix)key(postfix)' to their corresponding values.
+// The function keeps track of the keys that were already expanded and stops if it
+// detects a circular reference or a malformed expression of the form '(prefix)key'.
+func expand(s string, keys map[string]bool, prefix, postfix string, values map[string]string) (string, error) {
+ start := strings.Index(s, prefix)
+ if start == -1 {
+ return s, nil
+ }
+
+ keyStart := start + len(prefix)
+ keyLen := strings.Index(s[keyStart:], postfix)
+ if keyLen == -1 {
+ return "", fmt.Errorf("malformed expression")
+ }
+
+ end := keyStart + keyLen + len(postfix) - 1
+ key := s[keyStart : keyStart+keyLen]
+
+ // fmt.Printf("s:%q pp:%q start:%d end:%d keyStart:%d keyLen:%d key:%q\n", s, prefix + "..." + postfix, start, end, keyStart, keyLen, key)
+
+ if _, ok := keys[key]; ok {
+ return "", fmt.Errorf("circular reference")
+ }
+
+ val, ok := values[key]
+ if !ok {
+ val = os.Getenv(key)
+ }
+
+ // remember that we've seen the key
+ keys[key] = true
+
+ return expand(s[:start]+val+s[end+1:], keys, prefix, postfix, values)
+}
+
+// encode encodes a UTF-8 string to ISO-8859-1 and escapes some characters.
+func encode(s string, special string, enc Encoding) string {
+ switch enc {
+ case UTF8:
+ return encodeUtf8(s, special)
+ case ISO_8859_1:
+ return encodeIso(s, special)
+ default:
+ panic(fmt.Sprintf("unsupported encoding %v", enc))
+ }
+}
+
+func encodeUtf8(s string, special string) string {
+ v := ""
+ for pos := 0; pos < len(s); {
+ r, w := utf8.DecodeRuneInString(s[pos:])
+ pos += w
+ v += escape(r, special)
+ }
+ return v
+}
+
+func encodeIso(s string, special string) string {
+ var r rune
+ var w int
+ var v string
+ for pos := 0; pos < len(s); {
+ switch r, w = utf8.DecodeRuneInString(s[pos:]); {
+ case r < 1<<8: // single byte rune -> escape special chars only
+ v += escape(r, special)
+ case r < 1<<16: // two byte rune -> unicode literal
+ v += fmt.Sprintf("\\u%04x", r)
+ default: // more than two bytes per rune -> can't encode
+ v += "?"
+ }
+ pos += w
+ }
+ return v
+}
+
+func escape(r rune, special string) string {
+ switch r {
+ case '\f':
+ return "\\f"
+ case '\n':
+ return "\\n"
+ case '\r':
+ return "\\r"
+ case '\t':
+ return "\\t"
+ default:
+ if strings.ContainsRune(special, r) {
+ return "\\" + string(r)
+ }
+ return string(r)
+ }
+}
+
+func invalidKeyError(key string) error {
+ return fmt.Errorf("unknown property: %s", key)
+}
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