go.tools/cover: split parsing code out from cmd/cover

Split the profile parsing code out of cmd/cover into
a reusable package, to support third-party coverage
tools.

R=golang-dev, r, adg
CC=golang-dev
https://golang.org/cl/36050045

1 files changed, 190 insertions, 0 deletions

diff --git a/cover/profile.go b/cover/profile.go
new file mode 100644
index 000000000..1cbd73988
--- /dev/null
+++ b/cover/profile.go
@@ -0,0 +1,190 @@
+// Copyright 2013 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 cover provides support for parsing coverage profiles
+// generated by "go test -coverprofile=cover.out".
+package cover
+
+import (
+	"bufio"
+	"fmt"
+	"math"
+	"os"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+// Profile represents the profiling data for a specific file.
+type Profile struct {
+	FileName string
+	Mode     string
+	Blocks   []ProfileBlock
+}
+
+// ProfileBlock represents a single block of profiling data.
+type ProfileBlock struct {
+	StartLine, StartCol int
+	EndLine, EndCol     int
+	NumStmt, Count      int
+}
+
+type byFileName []*Profile
+
+func (p byFileName) Len() int           { return len(p) }
+func (p byFileName) Less(i, j int) bool { return p[i].FileName < p[j].FileName }
+func (p byFileName) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
+
+// ParseProfiles parses profile data in the specified file and returns a
+// Profile for each source file described therein.
+func ParseProfiles(fileName string) ([]*Profile, error) {
+	pf, err := os.Open(fileName)
+	if err != nil {
+		return nil, err
+	}
+	defer pf.Close()
+
+	files := make(map[string]*Profile)
+	buf := bufio.NewReader(pf)
+	// First line is "mode: foo", where foo is "set", "count", or "atomic".
+	// Rest of file is in the format
+	//	encoding/base64/base64.go:34.44,37.40 3 1
+	// where the fields are: name.go:line.column,line.column numberOfStatements count
+	s := bufio.NewScanner(buf)
+	mode := ""
+	for s.Scan() {
+		line := s.Text()
+		if mode == "" {
+			const p = "mode: "
+			if !strings.HasPrefix(line, p) || line == p {
+				return nil, fmt.Errorf("bad mode line: %v", line)
+			}
+			mode = line[len(p):]
+			continue
+		}
+		m := lineRe.FindStringSubmatch(line)
+		if m == nil {
+			return nil, fmt.Errorf("line %q doesn't match expected format: %v", m, lineRe)
+		}
+		fn := m[1]
+		p := files[fn]
+		if p == nil {
+			p = &Profile{
+				FileName: fn,
+				Mode:     mode,
+			}
+			files[fn] = p
+		}
+		p.Blocks = append(p.Blocks, ProfileBlock{
+			StartLine: toInt(m[2]),
+			StartCol:  toInt(m[3]),
+			EndLine:   toInt(m[4]),
+			EndCol:    toInt(m[5]),
+			NumStmt:   toInt(m[6]),
+			Count:     toInt(m[7]),
+		})
+	}
+	if err := s.Err(); err != nil {
+		return nil, err
+	}
+	for _, p := range files {
+		sort.Sort(blocksByStart(p.Blocks))
+	}
+	// Generate a sorted slice.
+	profiles := make([]*Profile, 0, len(files))
+	for _, profile := range files {
+		profiles = append(profiles, profile)
+	}
+	sort.Sort(byFileName(profiles))
+	return profiles, nil
+}
+
+type blocksByStart []ProfileBlock
+
+func (b blocksByStart) Len() int      { return len(b) }
+func (b blocksByStart) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
+func (b blocksByStart) Less(i, j int) bool {
+	bi, bj := b[i], b[j]
+	return bi.StartLine < bj.StartLine || bi.StartLine == bj.StartLine && bi.StartCol < bj.StartCol
+}
+
+var lineRe = regexp.MustCompile(`^(.+):([0-9]+).([0-9]+),([0-9]+).([0-9]+) ([0-9]+) ([0-9]+)$`)
+
+func toInt(s string) int {
+	i, err := strconv.Atoi(s)
+	if err != nil {
+		panic(err)
+	}
+	return i
+}
+
+// Boundary represents the position in a source file of the beginning or end of a
+// block as reported by the coverage profile. In HTML mode, it will correspond to
+// the opening or closing of a <span> tag and will be used to colorize the source
+type Boundary struct {
+	Offset int     // Location as a byte offset in the source file.
+	Start  bool    // Is this the start of a block?
+	Count  int     // Event count from the cover profile.
+	Norm   float64 // Count normalized to [0..1].
+}
+
+// Boundaries returns a Profile as a set of Boundary objects within the provided src.
+func (p *Profile) Boundaries(src []byte) (boundaries []Boundary) {
+	// Find maximum count.
+	max := 0
+	for _, b := range p.Blocks {
+		if b.Count > max {
+			max = b.Count
+		}
+	}
+	// Divisor for normalization.
+	divisor := math.Log(float64(max))
+
+	// boundary returns a Boundary, populating the Norm field with a normalized Count.
+	boundary := func(offset int, start bool, count int) Boundary {
+		b := Boundary{Offset: offset, Start: start, Count: count}
+		if !start || count == 0 {
+			return b
+		}
+		if max <= 1 {
+			b.Norm = 0.8 // Profile is in"set" mode; we want a heat map. Use cov8 in the CSS.
+		} else if count > 0 {
+			b.Norm = math.Log(float64(count)) / divisor
+		}
+		return b
+	}
+
+	line, col := 1, 2 // TODO: Why is this 2?
+	for si, bi := 0, 0; si < len(src) && bi < len(p.Blocks); {
+		b := p.Blocks[bi]
+		if b.StartLine == line && b.StartCol == col {
+			boundaries = append(boundaries, boundary(si, true, b.Count))
+		}
+		if b.EndLine == line && b.EndCol == col {
+			boundaries = append(boundaries, boundary(si, false, 0))
+			bi++
+			continue // Don't advance through src; maybe the next block starts here.
+		}
+		if src[si] == '\n' {
+			line++
+			col = 0
+		}
+		col++
+		si++
+	}
+	sort.Sort(boundariesByPos(boundaries))
+	return
+}
+
+type boundariesByPos []Boundary
+
+func (b boundariesByPos) Len() int      { return len(b) }
+func (b boundariesByPos) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
+func (b boundariesByPos) Less(i, j int) bool {
+	if b[i].Offset == b[j].Offset {
+		return !b[i].Start && b[j].Start
+	}
+	return b[i].Offset < b[j].Offset
+}