1 files changed, 131 insertions, 0 deletions
diff --git a/benchmark/parse/parse.go b/benchmark/parse/parse.go
new file mode 100644
index 0000000..b37e6f0
--- /dev/null
+++ b/benchmark/parse/parse.go
@@ -0,0 +1,131 @@
+// Copyright 2014 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 parse provides support for parsing benchmark results as
+// generated by 'go test -bench'.
+package parse // import "golang.org/x/tools/benchmark/parse"
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+// Flags used by Benchmark.Measured to indicate
+// which measurements a Benchmark contains.
+const (
+	NsPerOp = 1 << iota
+	MBPerS
+	AllocedBytesPerOp
+	AllocsPerOp
+)
+
+// Benchmark is one run of a single benchmark.
+type Benchmark struct {
+	Name              string  // benchmark name
+	N                 int     // number of iterations
+	NsPerOp           float64 // nanoseconds per iteration
+	AllocedBytesPerOp uint64  // bytes allocated per iteration
+	AllocsPerOp       uint64  // allocs per iteration
+	MBPerS            float64 // MB processed per second
+	Measured          int     // which measurements were recorded
+	Ord               int     // ordinal position within a benchmark run
+}
+
+// ParseLine extracts a Benchmark from a single line of testing.B
+// output.
+func ParseLine(line string) (*Benchmark, error) {
+	fields := strings.Fields(line)
+
+	// Two required, positional fields: Name and iterations.
+	if len(fields) < 2 {
+		return nil, fmt.Errorf("two fields required, have %d", len(fields))
+	}
+	if !strings.HasPrefix(fields[0], "Benchmark") {
+		return nil, fmt.Errorf(`first field does not start with "Benchmark"`)
+	}
+	n, err := strconv.Atoi(fields[1])
+	if err != nil {
+		return nil, err
+	}
+	b := &Benchmark{Name: fields[0], N: n}
+
+	// Parse any remaining pairs of fields; we've parsed one pair already.
+	for i := 1; i < len(fields)/2; i++ {
+		b.parseMeasurement(fields[i*2], fields[i*2+1])
+	}
+	return b, nil
+}
+
+func (b *Benchmark) parseMeasurement(quant string, unit string) {
+	switch unit {
+	case "ns/op":
+		if f, err := strconv.ParseFloat(quant, 64); err == nil {
+			b.NsPerOp = f
+			b.Measured |= NsPerOp
+		}
+	case "MB/s":
+		if f, err := strconv.ParseFloat(quant, 64); err == nil {
+			b.MBPerS = f
+			b.Measured |= MBPerS
+		}
+	case "B/op":
+		if i, err := strconv.ParseUint(quant, 10, 64); err == nil {
+			b.AllocedBytesPerOp = i
+			b.Measured |= AllocedBytesPerOp
+		}
+	case "allocs/op":
+		if i, err := strconv.ParseUint(quant, 10, 64); err == nil {
+			b.AllocsPerOp = i
+			b.Measured |= AllocsPerOp
+		}
+	}
+}
+
+func (b *Benchmark) String() string {
+	buf := new(bytes.Buffer)
+	fmt.Fprintf(buf, "%s %d", b.Name, b.N)
+	if (b.Measured & NsPerOp) != 0 {
+		fmt.Fprintf(buf, " %.2f ns/op", b.NsPerOp)
+	}
+	if (b.Measured & MBPerS) != 0 {
+		fmt.Fprintf(buf, " %.2f MB/s", b.MBPerS)
+	}
+	if (b.Measured & AllocedBytesPerOp) != 0 {
+		fmt.Fprintf(buf, " %d B/op", b.AllocedBytesPerOp)
+	}
+	if (b.Measured & AllocsPerOp) != 0 {
+		fmt.Fprintf(buf, " %d allocs/op", b.AllocsPerOp)
+	}
+	return buf.String()
+}
+
+// Set is a collection of benchmarks from one
+// testing.B run, keyed by name to facilitate comparison.
+type Set map[string][]*Benchmark
+
+// ParseSet extracts a Set from testing.B output.
+// ParseSet preserves the order of benchmarks that have identical
+// names.
+func ParseSet(r io.Reader) (Set, error) {
+	bb := make(Set)
+	scan := bufio.NewScanner(r)
+	ord := 0
+	for scan.Scan() {
+		if b, err := ParseLine(scan.Text()); err == nil {
+			b.Ord = ord
+			ord++
+			bb[b.Name] = append(bb[b.Name], b)
+		}
+	}
+
+	if err := scan.Err(); err != nil {
+		return nil, err
+	}
+
+	return bb, nil
+}