1 files changed, 304 insertions, 0 deletions
diff --git a/src/index/suffixarray/suffixarray_test.go b/src/index/suffixarray/suffixarray_test.go
new file mode 100644
index 000000000..644f00c75
--- /dev/null
+++ b/src/index/suffixarray/suffixarray_test.go
@@ -0,0 +1,304 @@
+// 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 suffixarray
+
+import (
+	"bytes"
+	"math/rand"
+	"regexp"
+	"sort"
+	"strings"
+	"testing"
+)
+
+type testCase struct {
+	name     string   // name of test case
+	source   string   // source to index
+	patterns []string // patterns to lookup
+}
+
+var testCases = []testCase{
+	{
+		"empty string",
+		"",
+		[]string{
+			"",
+			"foo",
+			"(foo)",
+			".*",
+			"a*",
+		},
+	},
+
+	{
+		"all a's",
+		"aaaaaaaaaa", // 10 a's
+		[]string{
+			"",
+			"a",
+			"aa",
+			"aaa",
+			"aaaa",
+			"aaaaa",
+			"aaaaaa",
+			"aaaaaaa",
+			"aaaaaaaa",
+			"aaaaaaaaa",
+			"aaaaaaaaaa",
+			"aaaaaaaaaaa", // 11 a's
+			".",
+			".*",
+			"a+",
+			"aa+",
+			"aaaa[b]?",
+			"aaa*",
+		},
+	},
+
+	{
+		"abc",
+		"abc",
+		[]string{
+			"a",
+			"b",
+			"c",
+			"ab",
+			"bc",
+			"abc",
+			"a.c",
+			"a(b|c)",
+			"abc?",
+		},
+	},
+
+	{
+		"barbara*3",
+		"barbarabarbarabarbara",
+		[]string{
+			"a",
+			"bar",
+			"rab",
+			"arab",
+			"barbar",
+			"bara?bar",
+		},
+	},
+
+	{
+		"typing drill",
+		"Now is the time for all good men to come to the aid of their country.",
+		[]string{
+			"Now",
+			"the time",
+			"to come the aid",
+			"is the time for all good men to come to the aid of their",
+			"to (come|the)?",
+		},
+	},
+
+	{
+		"godoc simulation",
+		"package main\n\nimport(\n    \"rand\"\n    ",
+		[]string{},
+	},
+}
+
+// find all occurrences of s in source; report at most n occurrences
+func find(src, s string, n int) []int {
+	var res []int
+	if s != "" && n != 0 {
+		// find at most n occurrences of s in src
+		for i := -1; n < 0 || len(res) < n; {
+			j := strings.Index(src[i+1:], s)
+			if j < 0 {
+				break
+			}
+			i += j + 1
+			res = append(res, i)
+		}
+	}
+	return res
+}
+
+func testLookup(t *testing.T, tc *testCase, x *Index, s string, n int) {
+	res := x.Lookup([]byte(s), n)
+	exp := find(tc.source, s, n)
+
+	// check that the lengths match
+	if len(res) != len(exp) {
+		t.Errorf("test %q, lookup %q (n = %d): expected %d results; got %d", tc.name, s, n, len(exp), len(res))
+	}
+
+	// if n >= 0 the number of results is limited --- unless n >= all results,
+	// we may obtain different positions from the Index and from find (because
+	// Index may not find the results in the same order as find) => in general
+	// we cannot simply check that the res and exp lists are equal
+
+	// check that each result is in fact a correct match and there are no duplicates
+	sort.Ints(res)
+	for i, r := range res {
+		if r < 0 || len(tc.source) <= r {
+			t.Errorf("test %q, lookup %q, result %d (n = %d): index %d out of range [0, %d[", tc.name, s, i, n, r, len(tc.source))
+		} else if !strings.HasPrefix(tc.source[r:], s) {
+			t.Errorf("test %q, lookup %q, result %d (n = %d): index %d not a match", tc.name, s, i, n, r)
+		}
+		if i > 0 && res[i-1] == r {
+			t.Errorf("test %q, lookup %q, result %d (n = %d): found duplicate index %d", tc.name, s, i, n, r)
+		}
+	}
+
+	if n < 0 {
+		// all results computed - sorted res and exp must be equal
+		for i, r := range res {
+			e := exp[i]
+			if r != e {
+				t.Errorf("test %q, lookup %q, result %d: expected index %d; got %d", tc.name, s, i, e, r)
+			}
+		}
+	}
+}
+
+func testFindAllIndex(t *testing.T, tc *testCase, x *Index, rx *regexp.Regexp, n int) {
+	res := x.FindAllIndex(rx, n)
+	exp := rx.FindAllStringIndex(tc.source, n)
+
+	// check that the lengths match
+	if len(res) != len(exp) {
+		t.Errorf("test %q, FindAllIndex %q (n = %d): expected %d results; got %d", tc.name, rx, n, len(exp), len(res))
+	}
+
+	// if n >= 0 the number of results is limited --- unless n >= all results,
+	// we may obtain different positions from the Index and from regexp (because
+	// Index may not find the results in the same order as regexp) => in general
+	// we cannot simply check that the res and exp lists are equal
+
+	// check that each result is in fact a correct match and the result is sorted
+	for i, r := range res {
+		if r[0] < 0 || r[0] > r[1] || len(tc.source) < r[1] {
+			t.Errorf("test %q, FindAllIndex %q, result %d (n == %d): illegal match [%d, %d]", tc.name, rx, i, n, r[0], r[1])
+		} else if !rx.MatchString(tc.source[r[0]:r[1]]) {
+			t.Errorf("test %q, FindAllIndex %q, result %d (n = %d): [%d, %d] not a match", tc.name, rx, i, n, r[0], r[1])
+		}
+	}
+
+	if n < 0 {
+		// all results computed - sorted res and exp must be equal
+		for i, r := range res {
+			e := exp[i]
+			if r[0] != e[0] || r[1] != e[1] {
+				t.Errorf("test %q, FindAllIndex %q, result %d: expected match [%d, %d]; got [%d, %d]",
+					tc.name, rx, i, e[0], e[1], r[0], r[1])
+			}
+		}
+	}
+}
+
+func testLookups(t *testing.T, tc *testCase, x *Index, n int) {
+	for _, pat := range tc.patterns {
+		testLookup(t, tc, x, pat, n)
+		if rx, err := regexp.Compile(pat); err == nil {
+			testFindAllIndex(t, tc, x, rx, n)
+		}
+	}
+}
+
+// index is used to hide the sort.Interface
+type index Index
+
+func (x *index) Len() int           { return len(x.sa) }
+func (x *index) Less(i, j int) bool { return bytes.Compare(x.at(i), x.at(j)) < 0 }
+func (x *index) Swap(i, j int)      { x.sa[i], x.sa[j] = x.sa[j], x.sa[i] }
+func (a *index) at(i int) []byte    { return a.data[a.sa[i]:] }
+
+func testConstruction(t *testing.T, tc *testCase, x *Index) {
+	if !sort.IsSorted((*index)(x)) {
+		t.Errorf("failed testConstruction %s", tc.name)
+	}
+}
+
+func equal(x, y *Index) bool {
+	if !bytes.Equal(x.data, y.data) {
+		return false
+	}
+	for i, j := range x.sa {
+		if j != y.sa[i] {
+			return false
+		}
+	}
+	return true
+}
+
+// returns the serialized index size
+func testSaveRestore(t *testing.T, tc *testCase, x *Index) int {
+	var buf bytes.Buffer
+	if err := x.Write(&buf); err != nil {
+		t.Errorf("failed writing index %s (%s)", tc.name, err)
+	}
+	size := buf.Len()
+	var y Index
+	if err := y.Read(&buf); err != nil {
+		t.Errorf("failed reading index %s (%s)", tc.name, err)
+	}
+	if !equal(x, &y) {
+		t.Errorf("restored index doesn't match saved index %s", tc.name)
+	}
+	return size
+}
+
+func TestIndex(t *testing.T) {
+	for _, tc := range testCases {
+		x := New([]byte(tc.source))
+		testConstruction(t, &tc, x)
+		testSaveRestore(t, &tc, x)
+		testLookups(t, &tc, x, 0)
+		testLookups(t, &tc, x, 1)
+		testLookups(t, &tc, x, 10)
+		testLookups(t, &tc, x, 2e9)
+		testLookups(t, &tc, x, -1)
+	}
+}
+
+// Of all possible inputs, the random bytes have the least amount of substring
+// repetition, and the repeated bytes have the most. For most algorithms,
+// the running time of every input will be between these two.
+func benchmarkNew(b *testing.B, random bool) {
+	b.StopTimer()
+	data := make([]byte, 1e6)
+	if random {
+		for i := range data {
+			data[i] = byte(rand.Intn(256))
+		}
+	}
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		New(data)
+	}
+}
+
+func BenchmarkNewIndexRandom(b *testing.B) {
+	benchmarkNew(b, true)
+}
+func BenchmarkNewIndexRepeat(b *testing.B) {
+	benchmarkNew(b, false)
+}
+
+func BenchmarkSaveRestore(b *testing.B) {
+	b.StopTimer()
+	r := rand.New(rand.NewSource(0x5a77a1)) // guarantee always same sequence
+	data := make([]byte, 1<<20)             // 1MB of data to index
+	for i := range data {
+		data[i] = byte(r.Intn(256))
+	}
+	x := New(data)
+	size := testSaveRestore(nil, nil, x)       // verify correctness
+	buf := bytes.NewBuffer(make([]byte, size)) // avoid growing
+	b.SetBytes(int64(size))
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		x.Write(buf)
+		var y Index
+		y.Read(buf)
+	}
+}