go/doc, godoc: move export filtering into go/doc

- exports.go contains a stripped-down (but semantically unchanged)
  version of the code in go/ast/filter.go for export filtering
- filter.go contains the documentation filtering code found before
  at the end of doc.go; this is simply a code move w/o any semantic
  changes
- godoc now relies on go/doc for export filtering when creating
  documentation. It still has a separate form of export filtering
  for showing the source code version. This needs to be consolidated
  (perhaps the source form view should just be removed?).
- Stripping of function bodies (stripFunctionBodies function of
  godoc.go) is now happening in doc.go (line 176).
- doc.NewPackageDoc has an extra parameter "exportsOnly. If set
  to false, the behavior is as before. This function is only called
  once in our source code; a gofix module is probably not warranted.
- Deleted doc.NewFileDoc - was never called.

This change is mostly a code move w/ some minimal tweaks. It should
not cause any changes to the behavior of godoc. It's a prerequisite
for extracting anonymous embedded fields.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5502072

5 files changed, 297 insertions, 127 deletions

diff --git a/src/cmd/godoc/godoc.go b/src/cmd/godoc/godoc.go
index f6626a00fb..1785a1f98f 100644
--- a/src/cmd/godoc/godoc.go
+++ b/src/cmd/godoc/godoc.go
@@ -961,16 +961,6 @@ func inList(name string, list []string) bool {
 	return false
 }
 
-func stripFunctionBodies(pkg *ast.Package) {
-	for _, f := range pkg.Files {
-		for _, d := range f.Decls {
-			if f, ok := d.(*ast.FuncDecl); ok {
-				f.Body = nil
-			}
-		}
-	}
-}
-
 // getPageInfo returns the PageInfo for a package directory abspath. If the
 // parameter genAST is set, an AST containing only the package exports is
 // computed (PageInfo.PAst), otherwise package documentation (PageInfo.Doc)
@@ -1096,13 +1086,17 @@ func (h *httpHandler) getPageInfo(abspath, relpath, pkgname string, mode PageInf
 	var past *ast.File
 	var pdoc *doc.PackageDoc
 	if pkg != nil {
-		if mode&noFiltering == 0 {
-			ast.PackageExports(pkg)
-		}
+		exportsOnly := mode&noFiltering == 0
 		if mode&showSource == 0 {
-			stripFunctionBodies(pkg)
-			pdoc = doc.NewPackageDoc(pkg, path.Clean(relpath)) // no trailing '/' in importpath
+			// show extracted documentation
+			pdoc = doc.NewPackageDoc(pkg, path.Clean(relpath), exportsOnly) // no trailing '/' in importpath
 		} else {
+			// show source code
+			// TODO(gri) Consider eliminating export filtering in this mode,
+			//           or perhaps eliminating the mode altogether.
+			if exportsOnly {
+				ast.PackageExports(pkg)
+			}
 			past = ast.MergePackageFiles(pkg, ast.FilterUnassociatedComments)
 		}
 	}
diff --git a/src/pkg/go/doc/Makefile b/src/pkg/go/doc/Makefile
index 2a421c3e6b..b27b85abea 100644
--- a/src/pkg/go/doc/Makefile
+++ b/src/pkg/go/doc/Makefile
@@ -9,6 +9,8 @@ GOFILES=\
 	comment.go\
 	doc.go\
 	example.go\
+	exports.go\
+	filter.go\
 
 include ../../../Make.pkg
 
diff --git a/src/pkg/go/doc/doc.go b/src/pkg/go/doc/doc.go
index 888fbe1bfb..1bb22416c7 100644
--- a/src/pkg/go/doc/doc.go
+++ b/src/pkg/go/doc/doc.go
@@ -13,6 +13,7 @@ import (
 )
 
 // ----------------------------------------------------------------------------
+// Collection of documentation info
 
 // embeddedType describes the type of an anonymous field.
 //
@@ -34,6 +35,10 @@ type typeInfo struct {
 	methods   map[string]*ast.FuncDecl
 }
 
+func (info *typeInfo) addEmbeddedType(embedded *typeInfo, isPtr bool) {
+	info.embedded = append(info.embedded, embeddedType{embedded, isPtr})
+}
+
 // docReader accumulates documentation for a single package.
 // It modifies the AST: Comments (declaration documentation)
 // that have been collected by the DocReader are set to nil
@@ -171,6 +176,9 @@ func setFunc(table map[string]*ast.FuncDecl, f *ast.FuncDecl) {
 }
 
 func (doc *docReader) addFunc(fun *ast.FuncDecl) {
+	// strip function body
+	fun.Body = nil
+
 	// determine if it should be associated with a type
 	if fun.Recv != nil {
 		// method
@@ -257,10 +265,9 @@ func (doc *docReader) addDecl(decl ast.Decl) {
 								// anonymous field - add corresponding type
 								// to the info and collect it in doc
 								name := baseTypeName(field.Type, true)
-								edoc := doc.lookupTypeInfo(name)
-								if edoc != nil {
+								if embedded := doc.lookupTypeInfo(name); embedded != nil {
 									_, ptr := field.Type.(*ast.StarExpr)
-									info.embedded = append(info.embedded, embeddedType{edoc, ptr})
+									info.addEmbeddedType(embedded, ptr)
 								}
 							}
 						}
@@ -313,19 +320,15 @@ func (doc *docReader) addFile(src *ast.File) {
 	src.Comments = nil // consumed unassociated comments - remove from ast.File node
 }
 
-func NewFileDoc(file *ast.File) *PackageDoc {
-	var r docReader
-	r.init(file.Name.Name)
-	r.addFile(file)
-	return r.newDoc("", nil)
-}
-
-func NewPackageDoc(pkg *ast.Package, importpath string) *PackageDoc {
+func NewPackageDoc(pkg *ast.Package, importpath string, exportsOnly bool) *PackageDoc {
 	var r docReader
 	r.init(pkg.Name)
 	filenames := make([]string, len(pkg.Files))
 	i := 0
 	for filename, f := range pkg.Files {
+		if exportsOnly {
+			r.fileExports(f)
+		}
 		r.addFile(f)
 		filenames[i] = filename
 		i++
@@ -674,104 +677,3 @@ func (doc *docReader) newDoc(importpath string, filenames []string) *PackageDoc
 	p.Bugs = makeBugDocs(doc.bugs)
 	return p
 }
-
-// ----------------------------------------------------------------------------
-// Filtering by name
-
-type Filter func(string) bool
-
-func matchFields(fields *ast.FieldList, f Filter) bool {
-	if fields != nil {
-		for _, field := range fields.List {
-			for _, name := range field.Names {
-				if f(name.Name) {
-					return true
-				}
-			}
-		}
-	}
-	return false
-}
-
-func matchDecl(d *ast.GenDecl, f Filter) bool {
-	for _, d := range d.Specs {
-		switch v := d.(type) {
-		case *ast.ValueSpec:
-			for _, name := range v.Names {
-				if f(name.Name) {
-					return true
-				}
-			}
-		case *ast.TypeSpec:
-			if f(v.Name.Name) {
-				return true
-			}
-			switch t := v.Type.(type) {
-			case *ast.StructType:
-				if matchFields(t.Fields, f) {
-					return true
-				}
-			case *ast.InterfaceType:
-				if matchFields(t.Methods, f) {
-					return true
-				}
-			}
-		}
-	}
-	return false
-}
-
-func filterValueDocs(a []*ValueDoc, f Filter) []*ValueDoc {
-	w := 0
-	for _, vd := range a {
-		if matchDecl(vd.Decl, f) {
-			a[w] = vd
-			w++
-		}
-	}
-	return a[0:w]
-}
-
-func filterFuncDocs(a []*FuncDoc, f Filter) []*FuncDoc {
-	w := 0
-	for _, fd := range a {
-		if f(fd.Name) {
-			a[w] = fd
-			w++
-		}
-	}
-	return a[0:w]
-}
-
-func filterTypeDocs(a []*TypeDoc, f Filter) []*TypeDoc {
-	w := 0
-	for _, td := range a {
-		n := 0 // number of matches
-		if matchDecl(td.Decl, f) {
-			n = 1
-		} else {
-			// type name doesn't match, but we may have matching consts, vars, factories or methods
-			td.Consts = filterValueDocs(td.Consts, f)
-			td.Vars = filterValueDocs(td.Vars, f)
-			td.Factories = filterFuncDocs(td.Factories, f)
-			td.Methods = filterFuncDocs(td.Methods, f)
-			n += len(td.Consts) + len(td.Vars) + len(td.Factories) + len(td.Methods)
-		}
-		if n > 0 {
-			a[w] = td
-			w++
-		}
-	}
-	return a[0:w]
-}
-
-// Filter eliminates documentation for names that don't pass through the filter f.
-// TODO: Recognize "Type.Method" as a name.
-//
-func (p *PackageDoc) Filter(f Filter) {
-	p.Consts = filterValueDocs(p.Consts, f)
-	p.Vars = filterValueDocs(p.Vars, f)
-	p.Types = filterTypeDocs(p.Types, f)
-	p.Funcs = filterFuncDocs(p.Funcs, f)
-	p.Doc = "" // don't show top-level package doc
-}
diff --git a/src/pkg/go/doc/exports.go b/src/pkg/go/doc/exports.go
new file mode 100644
index 0000000000..9cd186a9c7
--- /dev/null
+++ b/src/pkg/go/doc/exports.go
@@ -0,0 +1,167 @@
+// 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"
+
+func filterIdentList(list []*ast.Ident) []*ast.Ident {
+	j := 0
+	for _, x := range list {
+		if ast.IsExported(x.Name) {
+			list[j] = x
+			j++
+		}
+	}
+	return list[0:j]
+}
+
+func baseName(x ast.Expr) *ast.Ident {
+	switch t := x.(type) {
+	case *ast.Ident:
+		return t
+	case *ast.SelectorExpr:
+		if _, ok := t.X.(*ast.Ident); ok {
+			return t.Sel
+		}
+	case *ast.StarExpr:
+		return baseName(t.X)
+	}
+	return nil
+}
+
+func (doc *docReader) filterFieldList(fields *ast.FieldList) (removedFields bool) {
+	if fields == nil {
+		return false
+	}
+	list := fields.List
+	j := 0
+	for _, f := range list {
+		keepField := false
+		if len(f.Names) == 0 {
+			// anonymous field
+			name := baseName(f.Type)
+			keepField = name != nil && name.IsExported()
+		} else {
+			n := len(f.Names)
+			f.Names = filterIdentList(f.Names)
+			if len(f.Names) < n {
+				removedFields = true
+			}
+			keepField = len(f.Names) > 0
+		}
+		if keepField {
+			doc.filterType(f.Type)
+			list[j] = f
+			j++
+		}
+	}
+	if j < len(list) {
+		removedFields = true
+	}
+	fields.List = list[0:j]
+	return
+}
+
+func (doc *docReader) filterParamList(fields *ast.FieldList) bool {
+	if fields == nil {
+		return false
+	}
+	var b bool
+	for _, f := range fields.List {
+		if doc.filterType(f.Type) {
+			b = true
+		}
+	}
+	return b
+}
+
+func (doc *docReader) filterType(typ ast.Expr) bool {
+	switch t := typ.(type) {
+	case *ast.Ident:
+		return ast.IsExported(t.Name)
+	case *ast.ParenExpr:
+		return doc.filterType(t.X)
+	case *ast.ArrayType:
+		return doc.filterType(t.Elt)
+	case *ast.StructType:
+		if doc.filterFieldList(t.Fields) {
+			t.Incomplete = true
+		}
+		return len(t.Fields.List) > 0
+	case *ast.FuncType:
+		b1 := doc.filterParamList(t.Params)
+		b2 := doc.filterParamList(t.Results)
+		return b1 || b2
+	case *ast.InterfaceType:
+		if doc.filterFieldList(t.Methods) {
+			t.Incomplete = true
+		}
+		return len(t.Methods.List) > 0
+	case *ast.MapType:
+		b1 := doc.filterType(t.Key)
+		b2 := doc.filterType(t.Value)
+		return b1 || b2
+	case *ast.ChanType:
+		return doc.filterType(t.Value)
+	}
+	return false
+}
+
+func (doc *docReader) filterSpec(spec ast.Spec) bool {
+	switch s := spec.(type) {
+	case *ast.ValueSpec:
+		s.Names = filterIdentList(s.Names)
+		if len(s.Names) > 0 {
+			doc.filterType(s.Type)
+			return true
+		}
+	case *ast.TypeSpec:
+		if ast.IsExported(s.Name.Name) {
+			doc.filterType(s.Type)
+			return true
+		}
+	}
+	return false
+}
+
+func (doc *docReader) filterSpecList(list []ast.Spec) []ast.Spec {
+	j := 0
+	for _, s := range list {
+		if doc.filterSpec(s) {
+			list[j] = s
+			j++
+		}
+	}
+	return list[0:j]
+}
+
+func (doc *docReader) filterDecl(decl ast.Decl) bool {
+	switch d := decl.(type) {
+	case *ast.GenDecl:
+		d.Specs = doc.filterSpecList(d.Specs)
+		return len(d.Specs) > 0
+	case *ast.FuncDecl:
+		return ast.IsExported(d.Name.Name)
+	}
+	return false
+}
+
+// fileExports trims the AST for a Go file in place such that
+// only exported nodes remain. fileExports returns true if
+// there are exported declarations; otherwise it returns false.
+//
+func (doc *docReader) fileExports(src *ast.File) bool {
+	j := 0
+	for _, d := range src.Decls {
+		if doc.filterDecl(d) {
+			src.Decls[j] = d
+			j++
+		}
+	}
+	src.Decls = src.Decls[0:j]
+	return j > 0
+}
diff --git a/src/pkg/go/doc/filter.go b/src/pkg/go/doc/filter.go
new file mode 100644
index 0000000000..71c2ebb68b
--- /dev/null
+++ b/src/pkg/go/doc/filter.go
@@ -0,0 +1,105 @@
+// 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 doc
+
+import "go/ast"
+
+type Filter func(string) bool
+
+func matchFields(fields *ast.FieldList, f Filter) bool {
+	if fields != nil {
+		for _, field := range fields.List {
+			for _, name := range field.Names {
+				if f(name.Name) {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
+func matchDecl(d *ast.GenDecl, f Filter) bool {
+	for _, d := range d.Specs {
+		switch v := d.(type) {
+		case *ast.ValueSpec:
+			for _, name := range v.Names {
+				if f(name.Name) {
+					return true
+				}
+			}
+		case *ast.TypeSpec:
+			if f(v.Name.Name) {
+				return true
+			}
+			switch t := v.Type.(type) {
+			case *ast.StructType:
+				if matchFields(t.Fields, f) {
+					return true
+				}
+			case *ast.InterfaceType:
+				if matchFields(t.Methods, f) {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
+func filterValueDocs(a []*ValueDoc, f Filter) []*ValueDoc {
+	w := 0
+	for _, vd := range a {
+		if matchDecl(vd.Decl, f) {
+			a[w] = vd
+			w++
+		}
+	}
+	return a[0:w]
+}
+
+func filterFuncDocs(a []*FuncDoc, f Filter) []*FuncDoc {
+	w := 0
+	for _, fd := range a {
+		if f(fd.Name) {
+			a[w] = fd
+			w++
+		}
+	}
+	return a[0:w]
+}
+
+func filterTypeDocs(a []*TypeDoc, f Filter) []*TypeDoc {
+	w := 0
+	for _, td := range a {
+		n := 0 // number of matches
+		if matchDecl(td.Decl, f) {
+			n = 1
+		} else {
+			// type name doesn't match, but we may have matching consts, vars, factories or methods
+			td.Consts = filterValueDocs(td.Consts, f)
+			td.Vars = filterValueDocs(td.Vars, f)
+			td.Factories = filterFuncDocs(td.Factories, f)
+			td.Methods = filterFuncDocs(td.Methods, f)
+			n += len(td.Consts) + len(td.Vars) + len(td.Factories) + len(td.Methods)
+		}
+		if n > 0 {
+			a[w] = td
+			w++
+		}
+	}
+	return a[0:w]
+}
+
+// Filter eliminates documentation for names that don't pass through the filter f.
+// TODO: Recognize "Type.Method" as a name.
+//
+func (p *PackageDoc) Filter(f Filter) {
+	p.Consts = filterValueDocs(p.Consts, f)
+	p.Vars = filterValueDocs(p.Vars, f)
+	p.Types = filterTypeDocs(p.Types, f)
+	p.Funcs = filterFuncDocs(p.Funcs, f)
+	p.Doc = "" // don't show top-level package doc
+}