1 files changed, 205 insertions, 0 deletions
diff --git a/src/go/doc/exports.go b/src/go/doc/exports.go
new file mode 100644
index 000000000..1d3b466d8
--- /dev/null
+++ b/src/go/doc/exports.go
@@ -0,0 +1,205 @@
+// Copyright 2011 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.
+
+// This file implements export filtering of an AST.
+
+package doc
+
+import (
+	"go/ast"
+	"go/token"
+)
+
+// filterIdentList removes unexported names from list in place
+// and returns the resulting list. If blankOk is set, blank
+// identifiers are considered exported names.
+//
+func filterIdentList(list []*ast.Ident, blankOk bool) []*ast.Ident {
+	j := 0
+	for _, x := range list {
+		if ast.IsExported(x.Name) || (blankOk && x.Name == "_") {
+			list[j] = x
+			j++
+		}
+	}
+	return list[0:j]
+}
+
+// removeErrorField removes anonymous fields named "error" from an interface.
+// This is called when "error" has been determined to be a local name,
+// not the predeclared type.
+//
+func removeErrorField(ityp *ast.InterfaceType) {
+	list := ityp.Methods.List // we know that ityp.Methods != nil
+	j := 0
+	for _, field := range list {
+		keepField := true
+		if n := len(field.Names); n == 0 {
+			// anonymous field
+			if fname, _ := baseTypeName(field.Type); fname == "error" {
+				keepField = false
+			}
+		}
+		if keepField {
+			list[j] = field
+			j++
+		}
+	}
+	if j < len(list) {
+		ityp.Incomplete = true
+	}
+	ityp.Methods.List = list[0:j]
+}
+
+// filterFieldList removes unexported fields (field names) from the field list
+// in place and returns true if fields were removed. Anonymous fields are
+// recorded with the parent type. filterType is called with the types of
+// all remaining fields.
+//
+func (r *reader) filterFieldList(parent *namedType, fields *ast.FieldList, ityp *ast.InterfaceType) (removedFields bool) {
+	if fields == nil {
+		return
+	}
+	list := fields.List
+	j := 0
+	for _, field := range list {
+		keepField := false
+		if n := len(field.Names); n == 0 {
+			// anonymous field
+			fname := r.recordAnonymousField(parent, field.Type)
+			if ast.IsExported(fname) {
+				keepField = true
+			} else if ityp != nil && fname == "error" {
+				// possibly the predeclared error interface; keep
+				// it for now but remember this interface so that
+				// it can be fixed if error is also defined locally
+				keepField = true
+				r.remember(ityp)
+			}
+		} else {
+			field.Names = filterIdentList(field.Names, false)
+			if len(field.Names) < n {
+				removedFields = true
+			}
+			if len(field.Names) > 0 {
+				keepField = true
+			}
+		}
+		if keepField {
+			r.filterType(nil, field.Type)
+			list[j] = field
+			j++
+		}
+	}
+	if j < len(list) {
+		removedFields = true
+	}
+	fields.List = list[0:j]
+	return
+}
+
+// filterParamList applies filterType to each parameter type in fields.
+//
+func (r *reader) filterParamList(fields *ast.FieldList) {
+	if fields != nil {
+		for _, f := range fields.List {
+			r.filterType(nil, f.Type)
+		}
+	}
+}
+
+// filterType strips any unexported struct fields or method types from typ
+// in place. If fields (or methods) have been removed, the corresponding
+// struct or interface type has the Incomplete field set to true.
+//
+func (r *reader) filterType(parent *namedType, typ ast.Expr) {
+	switch t := typ.(type) {
+	case *ast.Ident:
+		// nothing to do
+	case *ast.ParenExpr:
+		r.filterType(nil, t.X)
+	case *ast.ArrayType:
+		r.filterType(nil, t.Elt)
+	case *ast.StructType:
+		if r.filterFieldList(parent, t.Fields, nil) {
+			t.Incomplete = true
+		}
+	case *ast.FuncType:
+		r.filterParamList(t.Params)
+		r.filterParamList(t.Results)
+	case *ast.InterfaceType:
+		if r.filterFieldList(parent, t.Methods, t) {
+			t.Incomplete = true
+		}
+	case *ast.MapType:
+		r.filterType(nil, t.Key)
+		r.filterType(nil, t.Value)
+	case *ast.ChanType:
+		r.filterType(nil, t.Value)
+	}
+}
+
+func (r *reader) filterSpec(spec ast.Spec, tok token.Token) bool {
+	switch s := spec.(type) {
+	case *ast.ImportSpec:
+		// always keep imports so we can collect them
+		return true
+	case *ast.ValueSpec:
+		// special case: consider blank constants as exported
+		// (work-around for issue 5397)
+		s.Names = filterIdentList(s.Names, tok == token.CONST)
+		if len(s.Names) > 0 {
+			r.filterType(nil, s.Type)
+			return true
+		}
+	case *ast.TypeSpec:
+		if name := s.Name.Name; ast.IsExported(name) {
+			r.filterType(r.lookupType(s.Name.Name), s.Type)
+			return true
+		} else if name == "error" {
+			// special case: remember that error is declared locally
+			r.errorDecl = true
+		}
+	}
+	return false
+}
+
+func (r *reader) filterSpecList(list []ast.Spec, tok token.Token) []ast.Spec {
+	j := 0
+	for _, s := range list {
+		if r.filterSpec(s, tok) {
+			list[j] = s
+			j++
+		}
+	}
+	return list[0:j]
+}
+
+func (r *reader) filterDecl(decl ast.Decl) bool {
+	switch d := decl.(type) {
+	case *ast.GenDecl:
+		d.Specs = r.filterSpecList(d.Specs, d.Tok)
+		return len(d.Specs) > 0
+	case *ast.FuncDecl:
+		// ok to filter these methods early because any
+		// conflicting method will be filtered here, too -
+		// thus, removing these methods early will not lead
+		// to the false removal of possible conflicts
+		return ast.IsExported(d.Name.Name)
+	}
+	return false
+}
+
+// fileExports removes unexported declarations from src in place.
+//
+func (r *reader) fileExports(src *ast.File) {
+	j := 0
+	for _, d := range src.Decls {
+		if r.filterDecl(d) {
+			src.Decls[j] = d
+			j++
+		}
+	}
+	src.Decls = src.Decls[0:j]
+}