Add a flags package.

R=gri
OCL=13399
CL=13399

3 files changed, 444 insertions, 3 deletions

diff --git a/src/lib/flag.go b/src/lib/flag.go
new file mode 100644
index 000000000..dc4863d98
--- /dev/null
+++ b/src/lib/flag.go
@@ -0,0 +1,439 @@
+// Copyright 2009 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 flag
+
+/*
+ * Flags
+ *
+ * Usage:
+ *	1) Define flags using flag.String(), Bool(), or Int(). Int flag values have type int64. Example:
+ *		import flag "flag"
+ *		var i int64
+ *		var fi *flag.Flag = flag.Int("flagname", 1234, &i, "help message for flagname")
+ *	The pointer may be nil; if non-nil, it points to a cell of the appropriate type to store the
+ *	flag's value.
+ *
+ *	2) After all flags are defined, call
+ *		flag.Parse()
+ *	to parse the command line into the defined flags.
+ *
+ *	3) Flags may then be used directly (getters are SVal, BVal, Ival) or through the associated
+ *	cell, if set:
+ *		print "fi has value ", fi.IVal(), "\n";
+ *		print "i has value ", i, "\n";
+ *
+ *	4) After parsing, flag.Arg(i) is the i'th argument after the flags.
+ *	Args are indexed from 0 up to flag.NArg().
+ *
+ *	Command line flag syntax:
+ *		-flag
+ *		-flag=x
+ *		-flag x
+ *	One or two minus signs may be used; they are equivalent.
+ *	A lone -- terminates the parsing of the command line.
+ *	Integer flags accept 1234, 0664, 0x1234 and may be negative.
+ *	Boolean flags may be 1, 0, t, f, true, false, TRUE, FALSE, True, False.
+ */
+
+export Bool, Int, String
+export Arg, NArg
+export Parse
+//export Flag.BVal BUG: variable exported but not defined: Flag.BVal
+//export Flag.SVal BUG: variable exported but not defined: Flag.SVal
+export Flag
+
+// BUG: ctoi, atoi, atob belong elsewhere
+func ctoi(c int64) int64 {
+	if '0' <= c && c <= '9' {
+		return c - '0'
+	}
+	if 'a' <= c && c <= 'f' {
+		return c - 'a'
+	}
+	if 'A' <= c && c <= 'F' {
+		return c - 'A'
+	}
+	return 1000   // too large for any base
+}
+
+func atoi(s string) (value int64, ok bool) {
+	if len(s) == 0 {
+		return 0, false
+	}
+	if s[0] == '-' {
+		n, t := atoi(s[1:len(s)]);
+		return -n, t
+	}
+	var base int64 = 10;
+	i := 0;
+	if s[0] == '0' {
+		base = 8
+		if len(s) > 1 && (s[1] == 'x' || s[1] == 'X') {
+			base = 16;
+			i += 2;
+		}
+	}
+	var n int64 = 0
+	for ; i < len(s); i++ {
+		k := ctoi(int64(s[i]));
+		if k >= base {
+			return 0, false
+		}
+		n = n * base + k
+	}
+	return n, true
+}
+
+func atob(str string) (value bool, ok bool) {
+	switch str {
+		case "1", "t", "T", "true", "TRUE", "True":
+			return true, true
+		case "0", "f", "F", "false", "FALSE", "False":
+			return false, true
+	}
+	return false, false
+}
+
+// -- Bool Value
+type BoolValue struct {
+	val bool;
+	p *bool;
+}
+
+func (b *BoolValue) AsBool() *BoolValue {
+	return b
+}
+
+func (b *BoolValue) AsInt() *IntValue {
+	return nil
+}
+
+func (b *BoolValue) AsString() *StringValue {
+	return nil
+}
+
+func (b *BoolValue) IsBool() bool {
+	return true
+}
+
+func (b *BoolValue) IsInt() bool {
+	return false
+}
+
+func (b *BoolValue) IsString() bool {
+	return false
+}
+
+func (b *BoolValue) ValidValue(str string) bool {
+	i, ok := atob(str);
+	return ok;
+}
+
+func (b *BoolValue) Set(val bool) {
+	if b.p != nil {
+		*b.p = val
+	}
+	b.val = val
+}
+
+func NewBoolValue(b bool, p *bool) *BoolValue {
+	v := new(BoolValue);
+	v.val = b;
+	v.p = p;
+	return v;
+}
+
+// -- Int Value
+type IntValue struct {
+	val	int64;
+	p	*int64;
+}
+
+func (i *IntValue) AsBool() *BoolValue {
+	return nil
+}
+
+func (i *IntValue) AsInt() *IntValue {
+	return i
+}
+
+func (i *IntValue) AsString() *StringValue{
+	return nil
+}
+
+func (i *IntValue) IsBool() bool {
+	return false
+}
+
+func (i *IntValue) IsInt() bool {
+	return true
+}
+
+func (i *IntValue) IsString() bool {
+	return false
+}
+
+func (i *IntValue) ValidValue(str string) bool {
+	k, ok := atoi(str);
+	return ok;
+}
+
+func (i *IntValue) Set(val int64) {
+	if i.p != nil {
+		*i.p = val
+	}
+	i.val = val
+}
+
+func
+NewIntValue(i int64, p *int64) *IntValue {
+	v := new(IntValue);
+	v.val = i;
+	v.p = p;
+	return v;
+}
+
+// -- String Value
+type StringValue struct {
+	val	string;
+	p	*string;
+}
+
+func (e *StringValue) AsBool() *BoolValue {
+	return nil
+}
+
+func (e *StringValue) AsInt() *IntValue {
+	return nil
+}
+
+func (s *StringValue) AsString() *StringValue{
+	return s
+}
+
+func (s *StringValue) IsBool() bool {
+	return false
+}
+
+func (s *StringValue) IsInt() bool {
+	return false
+}
+
+func (s *StringValue) IsString() bool {
+	return true
+}
+
+func (s *StringValue) ValidValue(str string) bool {
+	return true
+}
+
+func (s *StringValue) Set(val string) {
+	if s.p != nil {
+		*s.p = val
+	}
+	s.val = val
+}
+
+func NewStringValue(s string, p *string) *StringValue {
+	v := new(StringValue);
+	v.val = s;
+	v.p = p;
+	return v;
+}
+
+// -- Value interface
+type Value interface {
+	AsBool()	*BoolValue;
+	AsInt()	*IntValue;
+	AsString()	*StringValue;
+	IsBool()	bool;
+	IsInt()	bool;
+	IsString()	bool;
+	ValidValue(str string) bool;
+}
+
+// -- Flag structure (internal)
+type Flag struct {
+	name	string;
+	usage	string;
+	value	Value;
+}
+
+type Flags struct {
+	actual *map[string] *Flag;
+	formal *map[string] *Flag;
+	first_arg	int;
+}
+
+// --Customer's value getters
+func (f *Flag) BVal() bool {
+	if !f.value.IsBool() {
+		return false;
+	}
+	return f.value.AsBool().val;
+}
+
+func (f *Flag) IVal() int64 {
+	if !f.value.IsInt() {
+		return 0
+	}
+	return f.value.AsInt().val;
+}
+
+func (f *Flag) SVal() string {
+	if !f.value.IsString() {
+		return "???";
+	}
+	return f.value.AsString().val;
+}
+
+func New() *Flags {
+	f := new(Flags);
+	f.first_arg = 1;	// 0 is the program name, 1 is first arg
+	f.actual = new(map[string] *Flag);
+	f.formal = new(map[string] *Flag);
+	return f;
+}
+
+var flags *Flags = New();
+
+func Arg(i int) string {
+	i += flags.first_arg;
+	if i < 0 || i >= sys.argc() {
+		return "";
+	}
+	return sys.argv(i)
+}
+
+func NArg() int32 {
+	return sys.argc() - flags.first_arg
+}
+
+func Add(name string, value Value, usage string) *Flag {
+	f := new(Flag);
+	f.name = name;
+	f.usage = usage;
+	f.value = value;
+	dummy, alreadythere := flags.formal[name];
+	if alreadythere {
+		print "flag redefined: ", name, "\n";
+		panic "flag redefinition"
+	}
+	flags.formal[name] = f;
+	return f;
+}
+
+func Bool(name string, value bool, p *bool, usage string) *Flag {
+	return Add(name, NewBoolValue(value, p), usage);
+}
+
+func Int(name string, value int64, p *int64, usage string) *Flag {
+	return Add(name, NewIntValue(value, p), usage);
+}
+
+func String(name, value string, p *string, usage string) *Flag {
+	return Add(name, NewStringValue(value, p), usage);
+}
+
+func (f *Flags) ParseOne(index int) (ok bool, next int)
+{
+	s := sys.argv(index);
+	f.first_arg = index;  // until proven otherwise
+	if len(s) == 0 {
+		return false, -1
+	}
+	if s[0] != '-' {
+		return false, -1
+	}
+	num_minuses := 1;
+	if len(s) == 1 {
+		return false, -1
+	}
+	if s[1] == '-' {
+		num_minuses++
+		if len(s) == 2 {	// "--" terminates the flags
+			return false, index + 1
+		}
+	}
+	name := s[num_minuses : len(s)];
+	if len(name) == 0 || name[0] == '-' || name[0]=='=' {
+		print "bad flag syntax: ", s, "\n"
+		return false, -1
+	}
+
+	// it's a flag. does it have an argument?
+	has_value := false;
+	value := "";
+	for i := 1; i < len(name); i++ {  // equals cannot be first
+		if name[i] == '=' {
+			value = name[i+1 : len(name)];
+			has_value = true;
+			name = name[0 : i];
+			break;
+		}
+	}
+	flag, alreadythere := flags.actual[name];
+	if alreadythere {
+		print "flag specified twice: -", name, "\n"
+		return false, -1
+	}
+	m := flags.formal;
+	flag, alreadythere = m[name]; // BUG
+	if !alreadythere {
+		print "flag provided but not defined: -", name, "\n"
+		return false, -1
+	}
+	if !has_value && index < sys.argc()-1 && flag.value.ValidValue(sys.argv(index+1)) {
+		// value is the next arg
+		has_value = true;
+		index++;
+		value = sys.argv(index);
+	}
+	switch {
+		case flag.value.IsBool():
+			if has_value {
+				k, ok := atob(value);
+				if !ok {
+					print "invalid boolean value ", value, " for flag: -", name, "\n"
+					return false, -1
+				}
+				flag.value.AsBool().Set(k)
+			} else {
+				flag.value.AsBool().Set(true)
+			}
+		case flag.value.IsInt():
+			if !has_value {
+				print "flag needs an argument: -", name, "\n"
+				return false, -1
+			}
+			k, ok := atoi(value);
+			if !ok {
+				print "invalid integer value ", value, " for flag: -", name, "\n"
+				return false, -1
+			}
+			flag.value.AsInt().Set(k)
+		case flag.value.IsString():
+			if !has_value {
+				print "flag needs an argument: -", name, "\n"
+				return false, -1
+			}
+			flag.value.AsString().Set(value)
+	}
+	flags.actual[name] = flag;
+	return true, index + 1
+}
+
+func Parse() {
+	for i := 1; i < sys.argc();  {
+		ok, next := flags.ParseOne(i);
+		if next > 0 {
+			flags.first_arg = next;
+			i = next;
+		}
+		if !ok {
+			break
+		}
+	}
+}
diff --git a/src/lib/fmt.go b/src/lib/fmt.go
index 668d608d1..a123931e5 100644
--- a/src/lib/fmt.go
+++ b/src/lib/fmt.go
@@ -16,7 +16,7 @@ package fmt
 export Fmt, New;
 
 const NByte = 64;
-const NPows10 = 160;  // BUG: why not nelem(pows10);
+const NPows10 = 160;
 
 var ldigits string = "0123456789abcdef";  // BUG: Should be const
 var udigits string = "0123456789ABCDEF";  // BUG: Should be const
diff --git a/src/lib/make.bash b/src/lib/make.bash
index 88c97c138..d81d85193 100755
--- a/src/lib/make.bash
+++ b/src/lib/make.bash
@@ -5,6 +5,8 @@
 #!/bin/bash
 
 rm -f *.6
-6g fmt.go 
-6g container/vector.go
+for i in flag.go fmt.go container/vector.go
+do
+	6g $i
+done
 mv *.6 $GOROOT/pkg