346 lines
11 KiB
Go
346 lines
11 KiB
Go
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// Package minify relates MIME type to minifiers. Several minifiers are provided in the subpackages.
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package minify
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"mime"
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"net/http"
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"net/url"
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"os"
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"os/exec"
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"path"
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"regexp"
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"strings"
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"sync"
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"github.com/tdewolff/parse/v2"
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"github.com/tdewolff/parse/v2/buffer"
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)
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// Warning is used to report usage warnings such as using a deprecated feature
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var Warning = log.New(os.Stderr, "WARNING: ", 0)
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// ErrNotExist is returned when no minifier exists for a given mimetype.
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var ErrNotExist = errors.New("minifier does not exist for mimetype")
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////////////////////////////////////////////////////////////////
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// MinifierFunc is a function that implements Minifer.
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type MinifierFunc func(*M, io.Writer, io.Reader, map[string]string) error
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// Minify calls f(m, w, r, params)
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func (f MinifierFunc) Minify(m *M, w io.Writer, r io.Reader, params map[string]string) error {
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return f(m, w, r, params)
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}
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// Minifier is the interface for minifiers.
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// The *M parameter is used for minifying embedded resources, such as JS within HTML.
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type Minifier interface {
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Minify(*M, io.Writer, io.Reader, map[string]string) error
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}
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////////////////////////////////////////////////////////////////
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type patternMinifier struct {
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pattern *regexp.Regexp
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Minifier
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}
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type cmdMinifier struct {
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cmd *exec.Cmd
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}
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var cmdArgExtension = regexp.MustCompile(`^\.[0-9a-zA-Z]+`)
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func (c *cmdMinifier) Minify(_ *M, w io.Writer, r io.Reader, _ map[string]string) error {
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cmd := &exec.Cmd{}
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*cmd = *c.cmd // concurrency safety
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var in, out *os.File
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for i, arg := range cmd.Args {
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if j := strings.Index(arg, "$in"); j != -1 {
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var err error
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ext := cmdArgExtension.FindString(arg[j+3:])
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if in, err = ioutil.TempFile("", "minify-in-*"+ext); err != nil {
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return err
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}
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cmd.Args[i] = arg[:j] + in.Name() + arg[j+3+len(ext):]
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} else if j := strings.Index(arg, "$out"); j != -1 {
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var err error
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ext := cmdArgExtension.FindString(arg[j+4:])
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if out, err = ioutil.TempFile("", "minify-out-*"+ext); err != nil {
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return err
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}
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cmd.Args[i] = arg[:j] + out.Name() + arg[j+4+len(ext):]
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}
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}
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if in == nil {
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cmd.Stdin = r
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} else if _, err := io.Copy(in, r); err != nil {
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return err
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}
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if out == nil {
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cmd.Stdout = w
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} else {
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defer io.Copy(w, out)
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}
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stderr := &bytes.Buffer{}
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cmd.Stderr = stderr
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err := cmd.Run()
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if _, ok := err.(*exec.ExitError); ok {
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if stderr.Len() != 0 {
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err = fmt.Errorf("%s", stderr.String())
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}
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err = fmt.Errorf("command %s failed: %w", cmd.Path, err)
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}
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return err
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}
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////////////////////////////////////////////////////////////////
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// M holds a map of mimetype => function to allow recursive minifier calls of the minifier functions.
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type M struct {
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mutex sync.RWMutex
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literal map[string]Minifier
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pattern []patternMinifier
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URL *url.URL
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}
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// New returns a new M.
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func New() *M {
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return &M{
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sync.RWMutex{},
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map[string]Minifier{},
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[]patternMinifier{},
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nil,
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}
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}
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// Add adds a minifier to the mimetype => function map (unsafe for concurrent use).
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func (m *M) Add(mimetype string, minifier Minifier) {
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m.mutex.Lock()
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m.literal[mimetype] = minifier
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m.mutex.Unlock()
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}
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// AddFunc adds a minify function to the mimetype => function map (unsafe for concurrent use).
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func (m *M) AddFunc(mimetype string, minifier MinifierFunc) {
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m.mutex.Lock()
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m.literal[mimetype] = minifier
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m.mutex.Unlock()
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}
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// AddRegexp adds a minifier to the mimetype => function map (unsafe for concurrent use).
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func (m *M) AddRegexp(pattern *regexp.Regexp, minifier Minifier) {
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m.mutex.Lock()
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m.pattern = append(m.pattern, patternMinifier{pattern, minifier})
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m.mutex.Unlock()
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}
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// AddFuncRegexp adds a minify function to the mimetype => function map (unsafe for concurrent use).
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func (m *M) AddFuncRegexp(pattern *regexp.Regexp, minifier MinifierFunc) {
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m.mutex.Lock()
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m.pattern = append(m.pattern, patternMinifier{pattern, minifier})
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m.mutex.Unlock()
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}
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// AddCmd adds a minify function to the mimetype => function map (unsafe for concurrent use) that executes a command to process the minification.
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// It allows the use of external tools like ClosureCompiler, UglifyCSS, etc. for a specific mimetype.
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func (m *M) AddCmd(mimetype string, cmd *exec.Cmd) {
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m.mutex.Lock()
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m.literal[mimetype] = &cmdMinifier{cmd}
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m.mutex.Unlock()
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}
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// AddCmdRegexp adds a minify function to the mimetype => function map (unsafe for concurrent use) that executes a command to process the minification.
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// It allows the use of external tools like ClosureCompiler, UglifyCSS, etc. for a specific mimetype regular expression.
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func (m *M) AddCmdRegexp(pattern *regexp.Regexp, cmd *exec.Cmd) {
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m.mutex.Lock()
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m.pattern = append(m.pattern, patternMinifier{pattern, &cmdMinifier{cmd}})
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m.mutex.Unlock()
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}
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// Match returns the pattern and minifier that gets matched with the mediatype.
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// It returns nil when no matching minifier exists.
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// It has the same matching algorithm as Minify.
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func (m *M) Match(mediatype string) (string, map[string]string, MinifierFunc) {
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m.mutex.RLock()
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defer m.mutex.RUnlock()
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mimetype, params := parse.Mediatype([]byte(mediatype))
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if minifier, ok := m.literal[string(mimetype)]; ok { // string conversion is optimized away
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return string(mimetype), params, minifier.Minify
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}
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for _, minifier := range m.pattern {
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if minifier.pattern.Match(mimetype) {
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return minifier.pattern.String(), params, minifier.Minify
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}
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}
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return string(mimetype), params, nil
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}
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// Minify minifies the content of a Reader and writes it to a Writer (safe for concurrent use).
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// An error is returned when no such mimetype exists (ErrNotExist) or when an error occurred in the minifier function.
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// Mediatype may take the form of 'text/plain', 'text/*', '*/*' or 'text/plain; charset=UTF-8; version=2.0'.
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func (m *M) Minify(mediatype string, w io.Writer, r io.Reader) error {
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mimetype, params := parse.Mediatype([]byte(mediatype))
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return m.MinifyMimetype(mimetype, w, r, params)
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}
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// MinifyMimetype minifies the content of a Reader and writes it to a Writer (safe for concurrent use).
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// It is a lower level version of Minify and requires the mediatype to be split up into mimetype and parameters.
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// It is mostly used internally by minifiers because it is faster (no need to convert a byte-slice to string and vice versa).
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func (m *M) MinifyMimetype(mimetype []byte, w io.Writer, r io.Reader, params map[string]string) error {
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m.mutex.RLock()
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defer m.mutex.RUnlock()
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if minifier, ok := m.literal[string(mimetype)]; ok { // string conversion is optimized away
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return minifier.Minify(m, w, r, params)
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}
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for _, minifier := range m.pattern {
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if minifier.pattern.Match(mimetype) {
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return minifier.Minify(m, w, r, params)
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}
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}
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return ErrNotExist
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}
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// Bytes minifies an array of bytes (safe for concurrent use). When an error occurs it return the original array and the error.
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// It returns an error when no such mimetype exists (ErrNotExist) or any error occurred in the minifier function.
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func (m *M) Bytes(mediatype string, v []byte) ([]byte, error) {
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out := buffer.NewWriter(make([]byte, 0, len(v)))
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if err := m.Minify(mediatype, out, buffer.NewReader(v)); err != nil {
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return v, err
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}
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return out.Bytes(), nil
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}
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// String minifies a string (safe for concurrent use). When an error occurs it return the original string and the error.
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// It returns an error when no such mimetype exists (ErrNotExist) or any error occurred in the minifier function.
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func (m *M) String(mediatype string, v string) (string, error) {
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out := buffer.NewWriter(make([]byte, 0, len(v)))
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if err := m.Minify(mediatype, out, buffer.NewReader([]byte(v))); err != nil {
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return v, err
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}
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return string(out.Bytes()), nil
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}
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// Reader wraps a Reader interface and minifies the stream.
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// Errors from the minifier are returned by the reader.
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func (m *M) Reader(mediatype string, r io.Reader) io.Reader {
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pr, pw := io.Pipe()
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go func() {
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if err := m.Minify(mediatype, pw, r); err != nil {
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pw.CloseWithError(err)
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} else {
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pw.Close()
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}
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}()
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return pr
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}
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// minifyWriter makes sure that errors from the minifier are passed down through Close (can be blocking).
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type minifyWriter struct {
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pw *io.PipeWriter
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wg sync.WaitGroup
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err error
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}
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// Write intercepts any writes to the writer.
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func (w *minifyWriter) Write(b []byte) (int, error) {
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return w.pw.Write(b)
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}
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// Close must be called when writing has finished. It returns the error from the minifier.
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func (w *minifyWriter) Close() error {
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w.pw.Close()
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w.wg.Wait()
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return w.err
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}
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// Writer wraps a Writer interface and minifies the stream.
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// Errors from the minifier are returned by Close on the writer.
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// The writer must be closed explicitly.
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func (m *M) Writer(mediatype string, w io.Writer) *minifyWriter {
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pr, pw := io.Pipe()
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mw := &minifyWriter{pw, sync.WaitGroup{}, nil}
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mw.wg.Add(1)
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go func() {
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defer mw.wg.Done()
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if err := m.Minify(mediatype, w, pr); err != nil {
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io.Copy(w, pr)
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mw.err = err
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}
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pr.Close()
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}()
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return mw
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}
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// minifyResponseWriter wraps an http.ResponseWriter and makes sure that errors from the minifier are passed down through Close (can be blocking).
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// All writes to the response writer are intercepted and minified on the fly.
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// http.ResponseWriter loses all functionality such as Pusher, Hijacker, Flusher, ...
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type minifyResponseWriter struct {
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http.ResponseWriter
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writer *minifyWriter
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m *M
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mediatype string
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}
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// WriteHeader intercepts any header writes and removes the Content-Length header.
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func (w *minifyResponseWriter) WriteHeader(status int) {
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w.ResponseWriter.Header().Del("Content-Length")
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w.ResponseWriter.WriteHeader(status)
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}
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// Write intercepts any writes to the response writer.
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// The first write will extract the Content-Type as the mediatype. Otherwise it falls back to the RequestURI extension.
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func (w *minifyResponseWriter) Write(b []byte) (int, error) {
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if w.writer == nil {
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// first write
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if mediatype := w.ResponseWriter.Header().Get("Content-Type"); mediatype != "" {
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w.mediatype = mediatype
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}
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w.writer = w.m.Writer(w.mediatype, w.ResponseWriter)
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}
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return w.writer.Write(b)
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}
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// Close must be called when writing has finished. It returns the error from the minifier.
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func (w *minifyResponseWriter) Close() error {
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if w.writer != nil {
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return w.writer.Close()
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}
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return nil
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}
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// ResponseWriter minifies any writes to the http.ResponseWriter.
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// http.ResponseWriter loses all functionality such as Pusher, Hijacker, Flusher, ...
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// Minification might be slower than just sending the original file! Caching is advised.
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func (m *M) ResponseWriter(w http.ResponseWriter, r *http.Request) *minifyResponseWriter {
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mediatype := mime.TypeByExtension(path.Ext(r.RequestURI))
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return &minifyResponseWriter{w, nil, m, mediatype}
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}
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// Middleware provides a middleware function that minifies content on the fly by intercepting writes to http.ResponseWriter.
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// http.ResponseWriter loses all functionality such as Pusher, Hijacker, Flusher, ...
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// Minification might be slower than just sending the original file! Caching is advised.
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func (m *M) Middleware(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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mw := m.ResponseWriter(w, r)
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defer mw.Close()
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next.ServeHTTP(mw, r)
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})
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}
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