position.go: test cases for token.Pos

- adjustments to position.go due to changed sort.Search semantics
- various minor fixes

R=rsc
CC=golang-dev, r
https://golang.org/cl/3079041

2 files changed, 167 insertions, 10 deletions

diff --git a/src/pkg/go/token/position.go b/src/pkg/go/token/position.go
index 85d490b060..00e9bbf801 100644
--- a/src/pkg/go/token/position.go
+++ b/src/pkg/go/token/position.go
@@ -94,7 +94,14 @@ func (p Pos) IsValid() bool {
 
 
 func searchFiles(a []*File, x int) int {
-	return sort.Search(len(a), func(i int) bool { return a[i].base <= x })
+	i := sort.Search(len(a), func(i int) bool { return a[i].base < x })
+	// TODO(gri) The code below is really unfortunate. With the old
+	//           semantics of sort.Search, it was possible to simply
+	//           return i! Need to rethink the Search API.
+	if i == 0 || i < len(a) && a[i].base == x {
+		return i
+	}
+	return i - 1
 }
 
 
@@ -150,9 +157,9 @@ func (f *File) AddLineInfo(offset int, filename string, line int) {
 //
 type File struct {
 	set  *FileSet
-	base int
-	size int
-	name string
+	name string // file name as provided to AddFile
+	base int    // Pos value range for this file is [base...base+size]
+	size int    // file size as provided to AddFile
 
 	// lines and infos are protected by set.mutex
 	lines []int
@@ -187,7 +194,7 @@ func (f *File) LineCount() int {
 //
 func (f *File) AddLine(offset int) {
 	f.set.mutex.Lock()
-	if i := len(f.lines); i == 0 || f.lines[i-1] < offset && offset <= f.size {
+	if i := len(f.lines); (i == 0 || f.lines[i-1] < offset) && offset <= f.size {
 		f.lines = append(f.lines, offset)
 	}
 	f.set.mutex.Unlock()
@@ -252,12 +259,26 @@ func (f *File) Position(offset int) Position {
 
 
 func searchUints(a []int, x int) int {
-	return sort.Search(len(a), func(i int) bool { return a[i] <= x })
+	i := sort.Search(len(a), func(i int) bool { return a[i] < x })
+	// TODO(gri) The code below is really unfortunate. With the old
+	//           semantics of sort.Search, it was possible to simply
+	//           return i! Need to rethink the Search API.
+	if i == 0 || i < len(a) && a[i] == x {
+		return i
+	}
+	return i - 1
 }
 
 
 func searchLineInfos(a []lineInfo, x int) int {
-	return sort.Search(len(a), func(i int) bool { return a[i].offset <= x })
+	i := sort.Search(len(a), func(i int) bool { return a[i].offset < x })
+	// TODO(gri) The code below is really unfortunate. With the old
+	//           semantics of sort.Search, it was possible to simply
+	//           return i! Need to rethink the Search API.
+	if i == 0 || i < len(a) && a[i].offset == x {
+		return i
+	}
+	return i - 1
 }
 
 
@@ -298,18 +319,18 @@ func NewFileSet() *FileSet {
 
 // AddFile adds a new file with a given filename and file size to a the
 // file set s and returns the file. Multiple files may have the same name.
-// File.Pos may be used to create file-specifiction position values from a
+// File.Pos may be used to create file-specific position values from a
 // file offset.
 //
 func (s *FileSet) AddFile(filename string, size int) *File {
 	s.mutex.Lock()
-	f := &File{s, s.base, size, filename, []int{0}, nil}
+	defer s.mutex.Unlock()
+	f := &File{s, filename, s.base, size, []int{0}, nil}
 	s.base += size + 1 // +1 because EOF also has a position
 	if s.base < 0 {
 		panic("token.Pos offset overflow (> 2G of source code in file set)")
 	}
 	s.index[f] = len(s.files)
 	s.files = append(s.files, f)
-	s.mutex.Unlock()
 	return f
 }
diff --git a/src/pkg/go/token/position_test.go b/src/pkg/go/token/position_test.go
new file mode 100644
index 0000000000..286819e267
--- /dev/null
+++ b/src/pkg/go/token/position_test.go
@@ -0,0 +1,136 @@
+// Copyright 2010 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 token
+
+import (
+	"fmt"
+	"testing"
+)
+
+
+func checkPos(t *testing.T, msg string, p, q Position) {
+	if p.Filename != q.Filename {
+		t.Errorf("%s: expected filename = %q; got %q", msg, q.Filename, p.Filename)
+	}
+	if p.Offset != q.Offset {
+		t.Errorf("%s: expected offset = %d; got %d", msg, q.Offset, p.Offset)
+	}
+	if p.Line != q.Line {
+		t.Errorf("%s: expected line = %d; got %d", msg, q.Line, p.Line)
+	}
+	if p.Column != q.Column {
+		t.Errorf("%s: expected column = %d; got %d", msg, q.Column, p.Column)
+	}
+}
+
+
+func TestNoPos(t *testing.T) {
+	if NoPos.IsValid() {
+		t.Errorf("NoPos should not be valid")
+	}
+	var fset *FileSet
+	checkPos(t, "nil NoPos", fset.Position(NoPos), Position{})
+	fset = NewFileSet()
+	checkPos(t, "fset NoPos", fset.Position(NoPos), Position{})
+}
+
+
+var tests = []struct {
+	filename string
+	size     int
+	lines    []int
+}{
+	{"a", 0, []int{}},
+	{"b", 5, []int{0}},
+	{"c", 10, []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}},
+	{"d", 100, []int{0, 5, 10, 20, 30, 70, 71, 72, 80, 85, 90, 99}},
+	{"e", 777, []int{0, 80, 100, 120, 130, 180, 267, 455, 500, 567, 620}},
+}
+
+
+func linecol(lines []int, offs int) (int, int) {
+	prevLineOffs := 0
+	for line, lineOffs := range lines {
+		if offs < lineOffs {
+			return line, offs - prevLineOffs + 1
+		}
+		prevLineOffs = lineOffs
+	}
+	return len(lines), offs - prevLineOffs + 1
+}
+
+
+func verifyPositions(t *testing.T, fset *FileSet, f *File, lines []int) {
+	for offs := 0; offs < f.Size(); offs++ {
+		p := f.Pos(offs)
+		offs2 := f.Offset(p)
+		if offs2 != offs {
+			t.Errorf("%s, Offset: expected offset %d; got %d", f.Name(), offs, offs2)
+		}
+		line, col := linecol(lines, offs)
+		msg := fmt.Sprintf("%s (offs = %d, p = %d)", f.Name(), offs, p)
+		checkPos(t, msg, f.Position(offs), Position{f.Name(), offs, line, col})
+		checkPos(t, msg, fset.Position(p), Position{f.Name(), offs, line, col})
+	}
+}
+
+
+func TestPositions(t *testing.T) {
+	fset := NewFileSet()
+	for _, test := range tests {
+		// add file and verify name and size
+		f := fset.AddFile(test.filename, test.size)
+		if f.Name() != test.filename {
+			t.Errorf("expected filename %q; got %q", test.filename, f.Name())
+		}
+		if f.Size() != test.size {
+			t.Errorf("%s: expected file size %d; got %d", f.Name(), test.size, f.Size())
+		}
+
+		// add lines individually and verify all positions
+		for i, offset := range test.lines {
+			f.AddLine(offset)
+			if f.LineCount() != i+1 {
+				t.Errorf("%s, AddLine: expected line count %d; got %d", f.Name(), i+1, f.LineCount())
+			}
+			// adding the same offset again should be ignored
+			f.AddLine(offset)
+			if f.LineCount() != i+1 {
+				t.Errorf("%s, AddLine: expected unchanged line count %d; got %d", f.Name(), i+1, f.LineCount())
+			}
+			verifyPositions(t, fset, f, test.lines[0:i+1])
+		}
+
+		// add lines at once and verify all positions
+		ok := f.SetLines(test.lines)
+		if !ok {
+			t.Errorf("%s: SetLines failed", f.Name())
+		}
+		if f.LineCount() != len(test.lines) {
+			t.Errorf("%s, SetLines: expected line count %d; got %d", f.Name(), len(test.lines), f.LineCount())
+		}
+		verifyPositions(t, fset, f, test.lines)
+	}
+}
+
+
+func TestLineInfo(t *testing.T) {
+	fset := NewFileSet()
+	f := fset.AddFile("foo", 500)
+	lines := []int{0, 42, 77, 100, 210, 220, 277, 300, 333, 401}
+	// add lines individually and provide alternative line information
+	for _, offs := range lines {
+		f.AddLine(offs)
+		f.AddLineInfo(offs, "bar", 42)
+	}
+	// verify positions for all offsets
+	for offs := 0; offs <= f.Size(); offs++ {
+		p := f.Pos(offs)
+		_, col := linecol(lines, offs)
+		msg := fmt.Sprintf("%s (offs = %d, p = %d)", f.Name(), offs, p)
+		checkPos(t, msg, f.Position(offs), Position{"bar", offs, 42, col})
+		checkPos(t, msg, fset.Position(p), Position{"bar", offs, 42, col})
+	}
+}