// 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) } } // WriteVersionedGoFile 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 and build tags for the current Unicode version, func (w *CodeWriter) WriteVersionedGoFile(filename, pkg string) { tags := buildTags() if tags != "" { filename = insertVersion(filename, UnicodeVersion()) } 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, tags); 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, tags 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, tags, 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) }