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Diffstat (limited to 'libgo/go/encoding/xml/read.go')
-rw-r--r-- | libgo/go/encoding/xml/read.go | 630 |
1 files changed, 630 insertions, 0 deletions
diff --git a/libgo/go/encoding/xml/read.go b/libgo/go/encoding/xml/read.go new file mode 100644 index 0000000..c6a3d75 --- /dev/null +++ b/libgo/go/encoding/xml/read.go @@ -0,0 +1,630 @@ +// Copyright 2009 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 xml + +import ( + "bytes" + "errors" + "fmt" + "io" + "reflect" + "strconv" + "strings" + "unicode" + "unicode/utf8" +) + +// BUG(rsc): Mapping between XML elements and data structures is inherently flawed: +// an XML element is an order-dependent collection of anonymous +// values, while a data structure is an order-independent collection +// of named values. +// See package json for a textual representation more suitable +// to data structures. + +// Unmarshal parses an XML element from r and uses the +// reflect library to fill in an arbitrary struct, slice, or string +// pointed at by val. Well-formed data that does not fit +// into val is discarded. +// +// For example, given these definitions: +// +// type Email struct { +// Where string `xml:"attr"` +// Addr string +// } +// +// type Result struct { +// XMLName xml.Name `xml:"result"` +// Name string +// Phone string +// Email []Email +// Groups []string `xml:"group>value"` +// } +// +// result := Result{Name: "name", Phone: "phone", Email: nil} +// +// unmarshalling the XML input +// +// <result> +// <email where="home"> +// <addr>gre@example.com</addr> +// </email> +// <email where='work'> +// <addr>gre@work.com</addr> +// </email> +// <name>Grace R. Emlin</name> +// <group> +// <value>Friends</value> +// <value>Squash</value> +// </group> +// <address>123 Main Street</address> +// </result> +// +// via Unmarshal(r, &result) is equivalent to assigning +// +// r = Result{xml.Name{"", "result"}, +// "Grace R. Emlin", // name +// "phone", // no phone given +// []Email{ +// Email{"home", "gre@example.com"}, +// Email{"work", "gre@work.com"}, +// }, +// []string{"Friends", "Squash"}, +// } +// +// Note that the field r.Phone has not been modified and +// that the XML <address> element was discarded. Also, the field +// Groups was assigned considering the element path provided in the +// field tag. +// +// Because Unmarshal uses the reflect package, it can only assign +// to exported (upper case) fields. Unmarshal uses a case-insensitive +// comparison to match XML element names to struct field names. +// +// Unmarshal maps an XML element to a struct using the following rules. +// In the rules, the tag of a field refers to the value associated with the +// key 'xml' in the struct field's tag (see the example above). +// +// * If the struct has a field of type []byte or string with tag "innerxml", +// Unmarshal accumulates the raw XML nested inside the element +// in that field. The rest of the rules still apply. +// +// * If the struct has a field named XMLName of type xml.Name, +// Unmarshal records the element name in that field. +// +// * If the XMLName field has an associated tag of the form +// "name" or "namespace-URL name", the XML element must have +// the given name (and, optionally, name space) or else Unmarshal +// returns an error. +// +// * If the XML element has an attribute whose name matches a +// struct field of type string with tag "attr", Unmarshal records +// the attribute value in that field. +// +// * If the XML element contains character data, that data is +// accumulated in the first struct field that has tag "chardata". +// The struct field may have type []byte or string. +// If there is no such field, the character data is discarded. +// +// * If the XML element contains comments, they are accumulated in +// the first struct field that has tag "comments". The struct +// field may have type []byte or string. If there is no such +// field, the comments are discarded. +// +// * If the XML element contains a sub-element whose name matches +// the prefix of a tag formatted as "a>b>c", unmarshal +// will descend into the XML structure looking for elements with the +// given names, and will map the innermost elements to that struct field. +// A tag starting with ">" is equivalent to one starting +// with the field name followed by ">". +// +// * If the XML element contains a sub-element whose name +// matches a field whose tag is neither "attr" nor "chardata", +// Unmarshal maps the sub-element to that struct field. +// Otherwise, if the struct has a field named Any, unmarshal +// maps the sub-element to that struct field. +// +// Unmarshal maps an XML element to a string or []byte by saving the +// concatenation of that element's character data in the string or +// []byte. +// +// Unmarshal maps an attribute value to a string or []byte by saving +// the value in the string or slice. +// +// Unmarshal maps an XML element to a slice by extending the length of +// the slice and mapping the element to the newly created value. +// +// Unmarshal maps an XML element or attribute value to a bool by +// setting it to the boolean value represented by the string. +// +// Unmarshal maps an XML element or attribute value to an integer or +// floating-point field by setting the field to the result of +// interpreting the string value in decimal. There is no check for +// overflow. +// +// Unmarshal maps an XML element to an xml.Name by recording the +// element name. +// +// Unmarshal maps an XML element to a pointer by setting the pointer +// to a freshly allocated value and then mapping the element to that value. +// +func Unmarshal(r io.Reader, val interface{}) error { + v := reflect.ValueOf(val) + if v.Kind() != reflect.Ptr { + return errors.New("non-pointer passed to Unmarshal") + } + p := NewParser(r) + elem := v.Elem() + err := p.unmarshal(elem, nil) + if err != nil { + return err + } + return nil +} + +// An UnmarshalError represents an error in the unmarshalling process. +type UnmarshalError string + +func (e UnmarshalError) Error() string { return string(e) } + +// A TagPathError represents an error in the unmarshalling process +// caused by the use of field tags with conflicting paths. +type TagPathError struct { + Struct reflect.Type + Field1, Tag1 string + Field2, Tag2 string +} + +func (e *TagPathError) Error() string { + return fmt.Sprintf("%s field %q with tag %q conflicts with field %q with tag %q", e.Struct, e.Field1, e.Tag1, e.Field2, e.Tag2) +} + +// The Parser's Unmarshal method is like xml.Unmarshal +// except that it can be passed a pointer to the initial start element, +// useful when a client reads some raw XML tokens itself +// but also defers to Unmarshal for some elements. +// Passing a nil start element indicates that Unmarshal should +// read the token stream to find the start element. +func (p *Parser) Unmarshal(val interface{}, start *StartElement) error { + v := reflect.ValueOf(val) + if v.Kind() != reflect.Ptr { + return errors.New("non-pointer passed to Unmarshal") + } + return p.unmarshal(v.Elem(), start) +} + +// fieldName strips invalid characters from an XML name +// to create a valid Go struct name. It also converts the +// name to lower case letters. +func fieldName(original string) string { + + var i int + //remove leading underscores, without exhausting all characters + for i = 0; i < len(original)-1 && original[i] == '_'; i++ { + } + + return strings.Map( + func(x rune) rune { + if x == '_' || unicode.IsDigit(x) || unicode.IsLetter(x) { + return unicode.ToLower(x) + } + return -1 + }, + original[i:]) +} + +// Unmarshal a single XML element into val. +func (p *Parser) unmarshal(val reflect.Value, start *StartElement) error { + // Find start element if we need it. + if start == nil { + for { + tok, err := p.Token() + if err != nil { + return err + } + if t, ok := tok.(StartElement); ok { + start = &t + break + } + } + } + + if pv := val; pv.Kind() == reflect.Ptr { + if pv.IsNil() { + pv.Set(reflect.New(pv.Type().Elem())) + } + val = pv.Elem() + } + + var ( + data []byte + saveData reflect.Value + comment []byte + saveComment reflect.Value + saveXML reflect.Value + saveXMLIndex int + saveXMLData []byte + sv reflect.Value + styp reflect.Type + fieldPaths map[string]pathInfo + ) + + switch v := val; v.Kind() { + default: + return errors.New("unknown type " + v.Type().String()) + + case reflect.Slice: + typ := v.Type() + if typ.Elem().Kind() == reflect.Uint8 { + // []byte + saveData = v + break + } + + // Slice of element values. + // Grow slice. + n := v.Len() + if n >= v.Cap() { + ncap := 2 * n + if ncap < 4 { + ncap = 4 + } + new := reflect.MakeSlice(typ, n, ncap) + reflect.Copy(new, v) + v.Set(new) + } + v.SetLen(n + 1) + + // Recur to read element into slice. + if err := p.unmarshal(v.Index(n), start); err != nil { + v.SetLen(n) + return err + } + return nil + + case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr, reflect.String: + saveData = v + + case reflect.Struct: + if _, ok := v.Interface().(Name); ok { + v.Set(reflect.ValueOf(start.Name)) + break + } + + sv = v + typ := sv.Type() + styp = typ + // Assign name. + if f, ok := typ.FieldByName("XMLName"); ok { + // Validate element name. + if tag := f.Tag.Get("xml"); tag != "" { + ns := "" + i := strings.LastIndex(tag, " ") + if i >= 0 { + ns, tag = tag[0:i], tag[i+1:] + } + if tag != start.Name.Local { + return UnmarshalError("expected element type <" + tag + "> but have <" + start.Name.Local + ">") + } + if ns != "" && ns != start.Name.Space { + e := "expected element <" + tag + "> in name space " + ns + " but have " + if start.Name.Space == "" { + e += "no name space" + } else { + e += start.Name.Space + } + return UnmarshalError(e) + } + } + + // Save + v := sv.FieldByIndex(f.Index) + if _, ok := v.Interface().(Name); ok { + v.Set(reflect.ValueOf(start.Name)) + } + } + + // Assign attributes. + // Also, determine whether we need to save character data or comments. + for i, n := 0, typ.NumField(); i < n; i++ { + f := typ.Field(i) + switch f.Tag.Get("xml") { + case "attr": + strv := sv.FieldByIndex(f.Index) + // Look for attribute. + val := "" + k := strings.ToLower(f.Name) + for _, a := range start.Attr { + if fieldName(a.Name.Local) == k { + val = a.Value + break + } + } + copyValue(strv, []byte(val)) + + case "comment": + if !saveComment.IsValid() { + saveComment = sv.FieldByIndex(f.Index) + } + + case "chardata": + if !saveData.IsValid() { + saveData = sv.FieldByIndex(f.Index) + } + + case "innerxml": + if !saveXML.IsValid() { + saveXML = sv.FieldByIndex(f.Index) + if p.saved == nil { + saveXMLIndex = 0 + p.saved = new(bytes.Buffer) + } else { + saveXMLIndex = p.savedOffset() + } + } + + default: + if tag := f.Tag.Get("xml"); strings.Contains(tag, ">") { + if fieldPaths == nil { + fieldPaths = make(map[string]pathInfo) + } + path := strings.ToLower(tag) + if strings.HasPrefix(tag, ">") { + path = strings.ToLower(f.Name) + path + } + if strings.HasSuffix(tag, ">") { + path = path[:len(path)-1] + } + err := addFieldPath(sv, fieldPaths, path, f.Index) + if err != nil { + return err + } + } + } + } + } + + // Find end element. + // Process sub-elements along the way. +Loop: + for { + var savedOffset int + if saveXML.IsValid() { + savedOffset = p.savedOffset() + } + tok, err := p.Token() + if err != nil { + return err + } + switch t := tok.(type) { + case StartElement: + // Sub-element. + // Look up by tag name. + if sv.IsValid() { + k := fieldName(t.Name.Local) + + if fieldPaths != nil { + if _, found := fieldPaths[k]; found { + if err := p.unmarshalPaths(sv, fieldPaths, k, &t); err != nil { + return err + } + continue Loop + } + } + + match := func(s string) bool { + // check if the name matches ignoring case + if strings.ToLower(s) != k { + return false + } + // now check that it's public + c, _ := utf8.DecodeRuneInString(s) + return unicode.IsUpper(c) + } + + f, found := styp.FieldByNameFunc(match) + if !found { // fall back to mop-up field named "Any" + f, found = styp.FieldByName("Any") + } + if found { + if err := p.unmarshal(sv.FieldByIndex(f.Index), &t); err != nil { + return err + } + continue Loop + } + } + // Not saving sub-element but still have to skip over it. + if err := p.Skip(); err != nil { + return err + } + + case EndElement: + if saveXML.IsValid() { + saveXMLData = p.saved.Bytes()[saveXMLIndex:savedOffset] + if saveXMLIndex == 0 { + p.saved = nil + } + } + break Loop + + case CharData: + if saveData.IsValid() { + data = append(data, t...) + } + + case Comment: + if saveComment.IsValid() { + comment = append(comment, t...) + } + } + } + + if err := copyValue(saveData, data); err != nil { + return err + } + + switch t := saveComment; t.Kind() { + case reflect.String: + t.SetString(string(comment)) + case reflect.Slice: + t.Set(reflect.ValueOf(comment)) + } + + switch t := saveXML; t.Kind() { + case reflect.String: + t.SetString(string(saveXMLData)) + case reflect.Slice: + t.Set(reflect.ValueOf(saveXMLData)) + } + + return nil +} + +func copyValue(dst reflect.Value, src []byte) (err error) { + // Helper functions for integer and unsigned integer conversions + var itmp int64 + getInt64 := func() bool { + itmp, err = strconv.Atoi64(string(src)) + // TODO: should check sizes + return err == nil + } + var utmp uint64 + getUint64 := func() bool { + utmp, err = strconv.Atoui64(string(src)) + // TODO: check for overflow? + return err == nil + } + var ftmp float64 + getFloat64 := func() bool { + ftmp, err = strconv.Atof64(string(src)) + // TODO: check for overflow? + return err == nil + } + + // Save accumulated data and comments + switch t := dst; t.Kind() { + case reflect.Invalid: + // Probably a comment, handled below + default: + return errors.New("cannot happen: unknown type " + t.Type().String()) + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + if !getInt64() { + return err + } + t.SetInt(itmp) + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: + if !getUint64() { + return err + } + t.SetUint(utmp) + case reflect.Float32, reflect.Float64: + if !getFloat64() { + return err + } + t.SetFloat(ftmp) + case reflect.Bool: + value, err := strconv.Atob(strings.TrimSpace(string(src))) + if err != nil { + return err + } + t.SetBool(value) + case reflect.String: + t.SetString(string(src)) + case reflect.Slice: + t.Set(reflect.ValueOf(src)) + } + return nil +} + +type pathInfo struct { + fieldIdx []int + complete bool +} + +// addFieldPath takes an element path such as "a>b>c" and fills the +// paths map with all paths leading to it ("a", "a>b", and "a>b>c"). +// It is okay for paths to share a common, shorter prefix but not ok +// for one path to itself be a prefix of another. +func addFieldPath(sv reflect.Value, paths map[string]pathInfo, path string, fieldIdx []int) error { + if info, found := paths[path]; found { + return tagError(sv, info.fieldIdx, fieldIdx) + } + paths[path] = pathInfo{fieldIdx, true} + for { + i := strings.LastIndex(path, ">") + if i < 0 { + break + } + path = path[:i] + if info, found := paths[path]; found { + if info.complete { + return tagError(sv, info.fieldIdx, fieldIdx) + } + } else { + paths[path] = pathInfo{fieldIdx, false} + } + } + return nil + +} + +func tagError(sv reflect.Value, idx1 []int, idx2 []int) error { + t := sv.Type() + f1 := t.FieldByIndex(idx1) + f2 := t.FieldByIndex(idx2) + return &TagPathError{t, f1.Name, f1.Tag.Get("xml"), f2.Name, f2.Tag.Get("xml")} +} + +// unmarshalPaths walks down an XML structure looking for +// wanted paths, and calls unmarshal on them. +func (p *Parser) unmarshalPaths(sv reflect.Value, paths map[string]pathInfo, path string, start *StartElement) error { + if info, _ := paths[path]; info.complete { + return p.unmarshal(sv.FieldByIndex(info.fieldIdx), start) + } + for { + tok, err := p.Token() + if err != nil { + return err + } + switch t := tok.(type) { + case StartElement: + k := path + ">" + fieldName(t.Name.Local) + if _, found := paths[k]; found { + if err := p.unmarshalPaths(sv, paths, k, &t); err != nil { + return err + } + continue + } + if err := p.Skip(); err != nil { + return err + } + case EndElement: + return nil + } + } + panic("unreachable") +} + +// Have already read a start element. +// Read tokens until we find the end element. +// Token is taking care of making sure the +// end element matches the start element we saw. +func (p *Parser) Skip() error { + for { + tok, err := p.Token() + if err != nil { + return err + } + switch tok.(type) { + case StartElement: + if err := p.Skip(); err != nil { + return err + } + case EndElement: + return nil + } + } + panic("unreachable") +} |