1 files changed, 121 insertions, 0 deletions
diff --git a/v2/trace.go b/v2/trace.go
new file mode 100644
index 0000000..cdb03a8
--- /dev/null
+++ b/v2/trace.go
@@ -0,0 +1,121 @@
+// Copyright 2020 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package classifier
+
+import (
+	"fmt"
+	"strings"
+)
+
+// This file contains routines for a simple trace execution mechanism.
+
+// TraceConfiguration specifies the configuration for tracing execution of the
+// license classifier.
+type TraceConfiguration struct {
+	// Comma-separated list of phases to be traced. Can use * for all phases.
+	TracePhases string
+	// Comma-separated list of licenses to be traced. Can use * as a suffix to
+	// match prefixes, or by itself to match all licenses.
+	TraceLicenses string
+
+	// Tracer specifies a TraceFunc used to capture tracing information.
+	// If not supplied, emits using fmt.Printf
+	Tracer        TraceFunc
+	tracePhases   map[string]bool
+	traceLicenses map[string]bool
+}
+
+func (t *TraceConfiguration) init() {
+	if t == nil {
+		return
+	}
+	// Sample the config values to create the lookup maps
+	t.traceLicenses = make(map[string]bool)
+	t.tracePhases = make(map[string]bool)
+
+	if len(t.TraceLicenses) > 0 {
+		for _, lic := range strings.Split(t.TraceLicenses, ",") {
+			t.traceLicenses[lic] = true
+		}
+	}
+
+	if len(t.TracePhases) > 0 {
+		for _, phase := range strings.Split(t.TracePhases, ",") {
+			t.tracePhases[phase] = true
+		}
+	}
+}
+
+var traceLicenses map[string]bool
+var tracePhases map[string]bool
+
+func (t *TraceConfiguration) shouldTrace(phase string) bool {
+	if t == nil {
+		return false
+	}
+	if t.tracePhases["*"] {
+		return true
+	}
+	return t.tracePhases[phase]
+}
+
+func (t *TraceConfiguration) isTraceLicense(lic string) bool {
+	if t == nil {
+		return false
+	}
+	if t.traceLicenses[lic] {
+		return true
+	}
+
+	for e := range t.traceLicenses {
+		if idx := strings.Index(e, "*"); idx != -1 {
+			if strings.HasPrefix(lic, e[0:idx]) {
+				return true
+			}
+		}
+	}
+
+	return false
+}
+
+func (t *TraceConfiguration) trace(f string, args ...interface{}) {
+	if t == nil || t.Tracer == nil {
+		fmt.Printf(f, args...)
+		fmt.Println()
+		return
+	}
+
+	t.Tracer(f, args...)
+}
+
+func (t *TraceConfiguration) traceSearchset(lic string) bool {
+	return t.isTraceLicense(lic) && t.shouldTrace("searchset")
+}
+
+func (t *TraceConfiguration) traceTokenize(lic string) bool {
+	return t.isTraceLicense(lic) && t.shouldTrace("tokenize")
+}
+
+func (t *TraceConfiguration) traceScoring(lic string) bool {
+	return t.isTraceLicense(lic) && t.shouldTrace("score")
+}
+
+func (t *TraceConfiguration) traceFrequency(lic string) bool {
+	return t.isTraceLicense(lic) && t.shouldTrace("frequency")
+}
+
+// TraceFunc works like fmt.Printf to emit tracing data for the
+// classifier.
+type TraceFunc func(string, ...interface{})