2 files changed, 234 insertions, 0 deletions
diff --git a/libgo/go/try/try.go b/libgo/go/try/try.go
new file mode 100644
index 000000000..af31d0d2c
--- /dev/null
+++ b/libgo/go/try/try.go
@@ -0,0 +1,174 @@
+// 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 try contains the executable part of the gotry command.
+// It is not intended for general use.
+package try
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"reflect"
+	"unicode"
+)
+
+var output io.Writer = os.Stdout // redirected when testing
+
+// Main is called directly from the gotry-generated Go source file to perform
+// the evaluations.
+func Main(pkg, firstArg string, functions map[string]interface{}, args []interface{}) {
+	switch len(args) {
+	case 0:
+		// Nothing to do.
+	case 1:
+		// Compiler has already evaluated the expression; just print the result.
+		printSlice(firstArg, args)
+	default:
+		// See if methods satisfy the expressions.
+		tryMethods(pkg, firstArg, args)
+		// See if functions satisfy the expressions.
+		for name, fn := range functions {
+			tryFunction(pkg, name, fn, args)
+		}
+	}
+}
+
+// printSlice prints the zeroth element of the args slice, which should (by construction)
+// itself be a slice of interface{}.
+func printSlice(firstArg string, args []interface{}) {
+	// Args should be length 1 and a slice.
+	if len(args) != 1 {
+		return
+	}
+	arg, ok := args[0].([]interface{})
+	if !ok {
+		return
+	}
+	fmt.Fprintf(output, "%s = ", firstArg)
+	if len(arg) > 1 {
+		fmt.Fprint(output, "(")
+	}
+	for i, a := range arg {
+		if i > 0 {
+			fmt.Fprint(output, ", ")
+		}
+		fmt.Fprintf(output, "%#v", a)
+	}
+	if len(arg) > 1 {
+		fmt.Fprint(output, ")")
+	}
+	fmt.Fprint(output, "\n")
+}
+
+// tryMethods sees if the zeroth arg has methods, and if so treats them as potential
+// functions to satisfy the remaining arguments.
+func tryMethods(pkg, firstArg string, args []interface{}) {
+	defer func() { recover() }()
+	// Is the first argument something with methods?
+	v := reflect.NewValue(args[0])
+	typ := v.Type()
+	if typ.NumMethod() == 0 {
+		return
+	}
+	for i := 0; i < typ.NumMethod(); i++ {
+		if unicode.IsUpper(int(typ.Method(i).Name[0])) {
+			tryMethod(pkg, firstArg, typ.Method(i), args)
+		}
+	}
+}
+
+// tryMethod converts a method to a function for tryOneFunction.
+func tryMethod(pkg, firstArg string, method reflect.Method, args []interface{}) {
+	rfn := method.Func
+	typ := method.Type
+	name := method.Name
+	tryOneFunction(pkg, firstArg, name, typ, rfn, args)
+}
+
+// tryFunction sees if fn satisfies the arguments.
+func tryFunction(pkg, name string, fn interface{}, args []interface{}) {
+	defer func() { recover() }()
+	rfn := reflect.NewValue(fn).(*reflect.FuncValue)
+	typ := rfn.Type().(*reflect.FuncType)
+	tryOneFunction(pkg, "", name, typ, rfn, args)
+}
+
+// tryOneFunction is the common code for tryMethod and tryFunction.
+func tryOneFunction(pkg, firstArg, name string, typ *reflect.FuncType, rfn *reflect.FuncValue, args []interface{}) {
+	// Any results?
+	if typ.NumOut() == 0 {
+		return // Nothing to do.
+	}
+	// Right number of arguments + results?
+	if typ.NumIn()+typ.NumOut() != len(args) {
+		return
+	}
+	// Right argument and result types?
+	for i, a := range args {
+		if i < typ.NumIn() {
+			if !compatible(a, typ.In(i)) {
+				return
+			}
+		} else {
+			if !compatible(a, typ.Out(i-typ.NumIn())) {
+				return
+			}
+		}
+	}
+	// Build the call args.
+	argsVal := make([]reflect.Value, typ.NumIn()+typ.NumOut())
+	for i, a := range args {
+		argsVal[i] = reflect.NewValue(a)
+	}
+	// Call the function and see if the results are as expected.
+	resultVal := rfn.Call(argsVal[:typ.NumIn()])
+	for i, v := range resultVal {
+		if !reflect.DeepEqual(v.Interface(), args[i+typ.NumIn()]) {
+			return
+		}
+	}
+	// Present the result including a godoc command to get more information.
+	firstIndex := 0
+	if firstArg != "" {
+		fmt.Fprintf(output, "%s.%s(", firstArg, name)
+		firstIndex = 1
+	} else {
+		fmt.Fprintf(output, "%s.%s(", pkg, name)
+	}
+	for i := firstIndex; i < typ.NumIn(); i++ {
+		if i > firstIndex {
+			fmt.Fprint(output, ", ")
+		}
+		fmt.Fprintf(output, "%#v", args[i])
+	}
+	fmt.Fprint(output, ") = ")
+	if typ.NumOut() > 1 {
+		fmt.Fprint(output, "(")
+	}
+	for i := 0; i < typ.NumOut(); i++ {
+		if i > 0 {
+			fmt.Fprint(output, ", ")
+		}
+		fmt.Fprintf(output, "%#v", resultVal[i].Interface())
+	}
+	if typ.NumOut() > 1 {
+		fmt.Fprint(output, ")")
+	}
+	fmt.Fprintf(output, "  // godoc %s %s\n", pkg, name)
+}
+
+// compatible reports whether the argument is compatible with the type.
+func compatible(arg interface{}, typ reflect.Type) bool {
+	if reflect.Typeof(arg) == typ {
+		return true
+	}
+	if arg == nil {
+		// nil is OK if the type is an interface.
+		if _, ok := typ.(*reflect.InterfaceType); ok {
+			return true
+		}
+	}
+	return false
+}
diff --git a/libgo/go/try/try_test.go b/libgo/go/try/try_test.go
new file mode 100644
index 000000000..617b2c7c3
--- /dev/null
+++ b/libgo/go/try/try_test.go
@@ -0,0 +1,60 @@
+// 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 try
+
+import (
+	"bytes"
+	"regexp" // Used as the package to try.
+	"testing"
+)
+
+// The global functions in package regexp at time of writing.
+// Doesn't need to be updated unless the entries in this list become invalid.
+var functions = map[string]interface{}{
+	"Compile":     regexp.Compile,
+	"Match":       regexp.Match,
+	"MatchString": regexp.MatchString,
+	"MustCompile": regexp.MustCompile,
+	"QuoteMeta":   regexp.QuoteMeta,
+}
+
+// A wraps arguments to make the test cases nicer to read.
+func A(args ...interface{}) []interface{} {
+	return args
+}
+
+type Test struct {
+	firstArg string // only needed if there is exactly one argument
+	result   string // minus final newline; might be just the godoc string
+	args     []interface{}
+}
+
+var testRE = regexp.MustCompile("a(.)(.)d")
+
+var tests = []Test{
+	// A simple expression.  The final value is a slice in case the expression is multivalue.
+	{"3+4", "3+4 = 7", A([]interface{}{7})},
+	// A search for a function.
+	{"", "regexp QuoteMeta", A("([])", `\(\[\]\)`)},
+	// A search for a function with multiple return values.
+	{"", "regexp MatchString", A("abc", "xabcd", true, nil)},
+	// Searches for methods.
+	{"", "regexp MatchString", A(testRE, "xabcde", true)},
+	{"", "regexp NumSubexp", A(testRE, 2)},
+}
+
+func TestAll(t *testing.T) {
+	re := regexp.MustCompile(".*// godoc ")
+	for _, test := range tests {
+		b := new(bytes.Buffer)
+		output = b
+		Main("regexp", test.firstArg, functions, test.args)
+		expect := test.result + "\n"
+		got := re.ReplaceAllString(b.String(), "")
+		if got != expect {
+			t.Errorf("expected %q; got %q", expect, got)
+		}
+	}
+}