--- /dev/null
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gen
+
+import (
+ "bytes"
+ "encoding/gob"
+ "fmt"
+ "hash"
+ "hash/fnv"
+ "io"
+ "log"
+ "os"
+ "reflect"
+ "strings"
+ "unicode"
+ "unicode/utf8"
+)
+
+// This file contains utilities for generating code.
+
+// TODO: other write methods like:
+// - slices, maps, types, etc.
+
+// CodeWriter is a utility for writing structured code. It computes the content
+// hash and size of written content. It ensures there are newlines between
+// written code blocks.
+type CodeWriter struct {
+ buf bytes.Buffer
+ Size int
+ Hash hash.Hash32 // content hash
+ gob *gob.Encoder
+ // For comments we skip the usual one-line separator if they are followed by
+ // a code block.
+ skipSep bool
+}
+
+func (w *CodeWriter) Write(p []byte) (n int, err error) {
+ return w.buf.Write(p)
+}
+
+// NewCodeWriter returns a new CodeWriter.
+func NewCodeWriter() *CodeWriter {
+ h := fnv.New32()
+ return &CodeWriter{Hash: h, gob: gob.NewEncoder(h)}
+}
+
+// WriteGoFile appends the buffer with the total size of all created structures
+// and writes it as a Go file to the the given file with the given package name.
+func (w *CodeWriter) WriteGoFile(filename, pkg string) {
+ f, err := os.Create(filename)
+ if err != nil {
+ log.Fatalf("Could not create file %s: %v", filename, err)
+ }
+ defer f.Close()
+ if _, err = w.WriteGo(f, pkg); err != nil {
+ log.Fatalf("Error writing file %s: %v", filename, err)
+ }
+}
+
+// WriteGo appends the buffer with the total size of all created structures and
+// writes it as a Go file to the the given writer with the given package name.
+func (w *CodeWriter) WriteGo(out io.Writer, pkg string) (n int, err error) {
+ sz := w.Size
+ w.WriteComment("Total table size %d bytes (%dKiB); checksum: %X\n", sz, sz/1024, w.Hash.Sum32())
+ defer w.buf.Reset()
+ return WriteGo(out, pkg, w.buf.Bytes())
+}
+
+func (w *CodeWriter) printf(f string, x ...interface{}) {
+ fmt.Fprintf(w, f, x...)
+}
+
+func (w *CodeWriter) insertSep() {
+ if w.skipSep {
+ w.skipSep = false
+ return
+ }
+ // Use at least two newlines to ensure a blank space between the previous
+ // block. WriteGoFile will remove extraneous newlines.
+ w.printf("\n\n")
+}
+
+// WriteComment writes a comment block. All line starts are prefixed with "//".
+// Initial empty lines are gobbled. The indentation for the first line is
+// stripped from consecutive lines.
+func (w *CodeWriter) WriteComment(comment string, args ...interface{}) {
+ s := fmt.Sprintf(comment, args...)
+ s = strings.Trim(s, "\n")
+
+ // Use at least two newlines to ensure a blank space between the previous
+ // block. WriteGoFile will remove extraneous newlines.
+ w.printf("\n\n// ")
+ w.skipSep = true
+
+ // strip first indent level.
+ sep := "\n"
+ for ; len(s) > 0 && (s[0] == '\t' || s[0] == ' '); s = s[1:] {
+ sep += s[:1]
+ }
+
+ strings.NewReplacer(sep, "\n// ", "\n", "\n// ").WriteString(w, s)
+
+ w.printf("\n")
+}
+
+func (w *CodeWriter) writeSizeInfo(size int) {
+ w.printf("// Size: %d bytes\n", size)
+}
+
+// WriteConst writes a constant of the given name and value.
+func (w *CodeWriter) WriteConst(name string, x interface{}) {
+ w.insertSep()
+ v := reflect.ValueOf(x)
+
+ switch v.Type().Kind() {
+ case reflect.String:
+ w.printf("const %s %s = ", name, typeName(x))
+ w.WriteString(v.String())
+ w.printf("\n")
+ default:
+ w.printf("const %s = %#v\n", name, x)
+ }
+}
+
+// WriteVar writes a variable of the given name and value.
+func (w *CodeWriter) WriteVar(name string, x interface{}) {
+ w.insertSep()
+ v := reflect.ValueOf(x)
+ oldSize := w.Size
+ sz := int(v.Type().Size())
+ w.Size += sz
+
+ switch v.Type().Kind() {
+ case reflect.String:
+ w.printf("var %s %s = ", name, typeName(x))
+ w.WriteString(v.String())
+ case reflect.Struct:
+ w.gob.Encode(x)
+ fallthrough
+ case reflect.Slice, reflect.Array:
+ w.printf("var %s = ", name)
+ w.writeValue(v)
+ w.writeSizeInfo(w.Size - oldSize)
+ default:
+ w.printf("var %s %s = ", name, typeName(x))
+ w.gob.Encode(x)
+ w.writeValue(v)
+ w.writeSizeInfo(w.Size - oldSize)
+ }
+ w.printf("\n")
+}
+
+func (w *CodeWriter) writeValue(v reflect.Value) {
+ x := v.Interface()
+ switch v.Kind() {
+ case reflect.String:
+ w.WriteString(v.String())
+ case reflect.Array:
+ // Don't double count: callers of WriteArray count on the size being
+ // added, so we need to discount it here.
+ w.Size -= int(v.Type().Size())
+ w.writeSlice(x, true)
+ case reflect.Slice:
+ w.writeSlice(x, false)
+ case reflect.Struct:
+ w.printf("%s{\n", typeName(v.Interface()))
+ t := v.Type()
+ for i := 0; i < v.NumField(); i++ {
+ w.printf("%s: ", t.Field(i).Name)
+ w.writeValue(v.Field(i))
+ w.printf(",\n")
+ }
+ w.printf("}")
+ default:
+ w.printf("%#v", x)
+ }
+}
+
+// WriteString writes a string literal.
+func (w *CodeWriter) WriteString(s string) {
+ s = strings.Replace(s, `\`, `\\`, -1)
+ io.WriteString(w.Hash, s) // content hash
+ w.Size += len(s)
+
+ const maxInline = 40
+ if len(s) <= maxInline {
+ w.printf("%q", s)
+ return
+ }
+
+ // We will render the string as a multi-line string.
+ const maxWidth = 80 - 4 - len(`"`) - len(`" +`)
+
+ // When starting on its own line, go fmt indents line 2+ an extra level.
+ n, max := maxWidth, maxWidth-4
+
+ // As per https://golang.org/issue/18078, the compiler has trouble
+ // compiling the concatenation of many strings, s0 + s1 + s2 + ... + sN,
+ // for large N. We insert redundant, explicit parentheses to work around
+ // that, lowering the N at any given step: (s0 + s1 + ... + s63) + (s64 +
+ // ... + s127) + etc + (etc + ... + sN).
+ explicitParens, extraComment := len(s) > 128*1024, ""
+ if explicitParens {
+ w.printf(`(`)
+ extraComment = "; the redundant, explicit parens are for https://golang.org/issue/18078"
+ }
+
+ // Print "" +\n, if a string does not start on its own line.
+ b := w.buf.Bytes()
+ if p := len(bytes.TrimRight(b, " \t")); p > 0 && b[p-1] != '\n' {
+ w.printf("\"\" + // Size: %d bytes%s\n", len(s), extraComment)
+ n, max = maxWidth, maxWidth
+ }
+
+ w.printf(`"`)
+
+ for sz, p, nLines := 0, 0, 0; p < len(s); {
+ var r rune
+ r, sz = utf8.DecodeRuneInString(s[p:])
+ out := s[p : p+sz]
+ chars := 1
+ if !unicode.IsPrint(r) || r == utf8.RuneError || r == '"' {
+ switch sz {
+ case 1:
+ out = fmt.Sprintf("\\x%02x", s[p])
+ case 2, 3:
+ out = fmt.Sprintf("\\u%04x", r)
+ case 4:
+ out = fmt.Sprintf("\\U%08x", r)
+ }
+ chars = len(out)
+ }
+ if n -= chars; n < 0 {
+ nLines++
+ if explicitParens && nLines&63 == 63 {
+ w.printf("\") + (\"")
+ }
+ w.printf("\" +\n\"")
+ n = max - len(out)
+ }
+ w.printf("%s", out)
+ p += sz
+ }
+ w.printf(`"`)
+ if explicitParens {
+ w.printf(`)`)
+ }
+}
+
+// WriteSlice writes a slice value.
+func (w *CodeWriter) WriteSlice(x interface{}) {
+ w.writeSlice(x, false)
+}
+
+// WriteArray writes an array value.
+func (w *CodeWriter) WriteArray(x interface{}) {
+ w.writeSlice(x, true)
+}
+
+func (w *CodeWriter) writeSlice(x interface{}, isArray bool) {
+ v := reflect.ValueOf(x)
+ w.gob.Encode(v.Len())
+ w.Size += v.Len() * int(v.Type().Elem().Size())
+ name := typeName(x)
+ if isArray {
+ name = fmt.Sprintf("[%d]%s", v.Len(), name[strings.Index(name, "]")+1:])
+ }
+ if isArray {
+ w.printf("%s{\n", name)
+ } else {
+ w.printf("%s{ // %d elements\n", name, v.Len())
+ }
+
+ switch kind := v.Type().Elem().Kind(); kind {
+ case reflect.String:
+ for _, s := range x.([]string) {
+ w.WriteString(s)
+ w.printf(",\n")
+ }
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+ reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+ // nLine and nBlock are the number of elements per line and block.
+ nLine, nBlock, format := 8, 64, "%d,"
+ switch kind {
+ case reflect.Uint8:
+ format = "%#02x,"
+ case reflect.Uint16:
+ format = "%#04x,"
+ case reflect.Uint32:
+ nLine, nBlock, format = 4, 32, "%#08x,"
+ case reflect.Uint, reflect.Uint64:
+ nLine, nBlock, format = 4, 32, "%#016x,"
+ case reflect.Int8:
+ nLine = 16
+ }
+ n := nLine
+ for i := 0; i < v.Len(); i++ {
+ if i%nBlock == 0 && v.Len() > nBlock {
+ w.printf("// Entry %X - %X\n", i, i+nBlock-1)
+ }
+ x := v.Index(i).Interface()
+ w.gob.Encode(x)
+ w.printf(format, x)
+ if n--; n == 0 {
+ n = nLine
+ w.printf("\n")
+ }
+ }
+ w.printf("\n")
+ case reflect.Struct:
+ zero := reflect.Zero(v.Type().Elem()).Interface()
+ for i := 0; i < v.Len(); i++ {
+ x := v.Index(i).Interface()
+ w.gob.EncodeValue(v)
+ if !reflect.DeepEqual(zero, x) {
+ line := fmt.Sprintf("%#v,\n", x)
+ line = line[strings.IndexByte(line, '{'):]
+ w.printf("%d: ", i)
+ w.printf(line)
+ }
+ }
+ case reflect.Array:
+ for i := 0; i < v.Len(); i++ {
+ w.printf("%d: %#v,\n", i, v.Index(i).Interface())
+ }
+ default:
+ panic("gen: slice elem type not supported")
+ }
+ w.printf("}")
+}
+
+// WriteType writes a definition of the type of the given value and returns the
+// type name.
+func (w *CodeWriter) WriteType(x interface{}) string {
+ t := reflect.TypeOf(x)
+ w.printf("type %s struct {\n", t.Name())
+ for i := 0; i < t.NumField(); i++ {
+ w.printf("\t%s %s\n", t.Field(i).Name, t.Field(i).Type)
+ }
+ w.printf("}\n")
+ return t.Name()
+}
+
+// typeName returns the name of the go type of x.
+func typeName(x interface{}) string {
+ t := reflect.ValueOf(x).Type()
+ return strings.Replace(fmt.Sprint(t), "main.", "", 1)
+}
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