lang: funcs: Add regexp package and match function

This adds a simple regexp match function. This will be useful for
regexp based name classification, if you're into that sort of thing.

examples/lang/regexp0.mcl

@@ -0,0 +1,10 @@
+import "fmt"
+import "regexp"
+
+# test with:
+# ./mgmt run --hostname foo.example.com --tmp-prefix lang --lang examples/lang/regexp0.mcl
+# ./mgmt run --hostname db1.example.com --tmp-prefix lang --lang examples/lang/regexp0.mcl
+print "regexp" {
+	# TODO: add a heredoc string to avoid needing to escape the \ chars
+	msg => fmt.printf("match: %t", regexp.match("^db\\d+\\.example\\.com$", $hostname)),
+}

lang/funcs/core/core.go

@@ -24,6 +24,7 @@ import (
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/fmt"
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/math"
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/os"
+	_ "github.com/purpleidea/mgmt/lang/funcs/core/regexp"
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/strings"
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/sys"
 	_ "github.com/purpleidea/mgmt/lang/funcs/core/world"

lang/funcs/core/regexp/match_func.go

@@ -0,0 +1,51 @@
+// Mgmt
+// Copyright (C) 2013-2019+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package coreregexp
+
+import (
+	"regexp"
+
+	"github.com/purpleidea/mgmt/lang/funcs/simple"
+	"github.com/purpleidea/mgmt/lang/types"
+	"github.com/purpleidea/mgmt/util/errwrap"
+)
+
+func init() {
+	simple.ModuleRegister(moduleName, "match", &types.FuncValue{
+		T: types.NewType("func(pattern str, s str) bool"),
+		V: Match,
+	})
+}
+
+// Match matches whether a string matches the regexp pattern.
+func Match(input []types.Value) (types.Value, error) {
+	pattern := input[0].Str()
+	s := input[1].Str()
+
+	// TODO: We could make this more efficient with the regular function API
+	// by only compiling the pattern when it changes.
+	re, err := regexp.Compile(pattern)
+	if err != nil {
+		return nil, errwrap.Wrapf(err, "pattern did not compile")
+	}
+
+	result := re.MatchString(s)
+	return &types.BoolValue{
+		V: result,
+	}, nil
+}

lang/funcs/core/regexp/match_func_test.go

@@ -0,0 +1,75 @@
+// Mgmt
+// Copyright (C) 2013-2019+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package coreregexp
+
+import (
+	"testing"
+
+	"github.com/purpleidea/mgmt/lang/types"
+)
+
+func TestMatch0(t *testing.T) {
+	values := []struct {
+		pattern  string
+		s        string
+		expected bool
+	}{
+		{
+			"(mgmt){2}",
+			"mgmt",
+			false,
+		},
+		{
+			"(mgmt){2}",
+			"mgmtmgmt",
+			true,
+		},
+		{
+			"(mgmt){2}",
+			"mgmtmgmtmgmt",
+			true,
+		},
+		{
+			`^db\d+\.example\.com$`,
+			"db1.example.com",
+			true,
+		},
+		{
+			`^db\d+\.example\.com$`,
+			"dbX.example.com",
+			false,
+		},
+		{
+			`^db\d+\.example\.com$`,
+			"db1.exampleXcom",
+			false,
+		},
+	}
+
+	for i, x := range values {
+		pattern := &types.StrValue{V: x.pattern}
+		s := &types.StrValue{V: x.s}
+		val, err := Match([]types.Value{pattern, s})
+		if err != nil {
+			t.Errorf("test index %d failed with: %+v", i, err)
+		}
+		if a, b := x.expected, val.Bool(); a != b {
+			t.Errorf("test index %d expected %t, got %t", i, a, b)
+		}
+	}
+}

lang/funcs/core/regexp/regexp.go

@@ -0,0 +1,23 @@
+// Mgmt
+// Copyright (C) 2013-2019+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package coreregexp
+
+const (
+	// moduleName is the prefix given to all the functions in this module.
+	moduleName = "regexp"
+)