Implement numeric conversion.

This pull-request closes #80, by implementing support for numeric conversion - decimal to binary/hex, and the other way round.
skx · Nov 12, 2022 · 6fa397d · 6fa397d
1 parent 4db7a29
commit 6fa397d
Show file tree

Hide file tree

Showing 3 changed files with 214 additions and 7 deletions.
diff --git a/builtins/builtins.go b/builtins/builtins.go
@@ -100,6 +100,7 @@ func PopulateEnvironment(env *env.Environment) {
 	env.Set("<", &primitive.Procedure{F: ltFn, Help: helpMap["<"], Args: []primitive.Symbol{primitive.Symbol("a"), primitive.Symbol("b")}})
 	env.Set("=", &primitive.Procedure{F: equalsFn, Help: helpMap["="], Args: []primitive.Symbol{primitive.Symbol("arg1"), primitive.Symbol("arg2 .. argN")}})
 	env.Set("arch", &primitive.Procedure{F: archFn, Help: helpMap["arch"]})
+	env.Set("base", &primitive.Procedure{F: baseFn, Help: helpMap["base"], Args: []primitive.Symbol{primitive.Symbol("number"), primitive.Symbol("base")}})
 	env.Set("car", &primitive.Procedure{F: carFn, Help: helpMap["car"], Args: []primitive.Symbol{primitive.Symbol("list")}})
 	env.Set("cdr", &primitive.Procedure{F: cdrFn, Help: helpMap["cdr"], Args: []primitive.Symbol{primitive.Symbol("list")}})
 	env.Set("char=", &primitive.Procedure{F: charEqualsFn, Help: helpMap["char="], Args: []primitive.Symbol{primitive.Symbol("a"), primitive.Symbol("b")}})
@@ -131,7 +132,8 @@ func PopulateEnvironment(env *env.Environment) {
 	env.Set("ms", &primitive.Procedure{F: msFn, Help: helpMap["ms"]})
 	env.Set("nil?", &primitive.Procedure{F: nilFn, Help: helpMap["nil?"], Args: []primitive.Symbol{primitive.Symbol("object")}})
 	env.Set("now", &primitive.Procedure{F: nowFn, Help: helpMap["now"]})
-	env.Set("nth", &primitive.Procedure{F: nthFn, Help: helpMap["nth"],Args: []primitive.Symbol{primitive.Symbol("list"), primitive.Symbol("offset")}})
+	env.Set("nth", &primitive.Procedure{F: nthFn, Help: helpMap["nth"], Args: []primitive.Symbol{primitive.Symbol("list"), primitive.Symbol("offset")}})
+	env.Set("number", &primitive.Procedure{F: numberFn, Help: helpMap["number"], Args: []primitive.Symbol{primitive.Symbol("str")}})
 	env.Set("ord", &primitive.Procedure{F: ordFn, Help: helpMap["ord"], Args: []primitive.Symbol{primitive.Symbol("char")}})
 	env.Set("os", &primitive.Procedure{F: osFn, Help: helpMap["os"]})
 	env.Set("print", &primitive.Procedure{F: printFn, Help: helpMap["print"], Args: []primitive.Symbol{primitive.Symbol("arg1..argN")}})
@@ -154,6 +156,27 @@ func archFn(env *env.Environment, args []primitive.Primitive) primitive.Primitiv
 	return primitive.String(runtime.GOARCH)
 }
 
+// baseFn implements (base)
+func baseFn(env *env.Environment, args []primitive.Primitive) primitive.Primitive {
+	if len(args) != 2 {
+		return primitive.ArityError()
+	}
+
+	// Get the value
+	n, ok := args[0].(primitive.Number)
+	if !ok {
+		return primitive.Error("argument not a number")
+	}
+
+	// Get the base
+	base, ok2 := args[1].(primitive.Number)
+	if !ok2 {
+		return primitive.Error("argument not a number")
+	}
+
+	return primitive.String(strconv.FormatInt(int64(n), int(base)))
+}
+
 // carFn implements "car"
 func carFn(env *env.Environment, args []primitive.Primitive) primitive.Primitive {
 
@@ -1173,7 +1196,6 @@ func nowFn(env *env.Environment, args []primitive.Primitive) primitive.Primitive
 // nthFn is the implementation of `(nth..)`
 func nthFn(env *env.Environment, args []primitive.Primitive) primitive.Primitive {
 
-
 	// We need two arguments.
 	if len(args) != 2 {
 		return primitive.ArityError()
@@ -1201,6 +1223,40 @@ func nthFn(env *env.Environment, args []primitive.Primitive) primitive.Primitive
 	return primitive.Error("out of bounds")
 }
 
+// numberFn is the implementation of (number ..)
+func numberFn(env *env.Environment, args []primitive.Primitive) primitive.Primitive {
+	// we only accept a single parameter
+	if len(args) != 1 {
+		return primitive.ArityError()
+	}
+
+	// The argument must be a string
+	str, ok := args[0].(primitive.String)
+	if !ok {
+		return primitive.Error("argument not a string")
+	}
+
+	// Lower-case so our prefix-matching works
+	s := strings.ToLower(str.ToString())
+	if strings.HasPrefix(s, "0x") || strings.HasPrefix(s, "0b") {
+
+		// If so then parse as an integer
+		n, err := strconv.ParseInt(s, 0, 32)
+		if err == nil {
+			return primitive.Number(n)
+		}
+	}
+
+	// Is it a number?
+	f, err := strconv.ParseFloat(s, 64)
+	if err == nil {
+
+		return primitive.Number(f)
+	}
+
+	return primitive.Error(fmt.Sprintf("failed to convert %s to number", args[0].ToString()))
+}
+
 // ordFn is the implementation of (ord ..)
 func ordFn(env *env.Environment, args []primitive.Primitive) primitive.Primitive {
 

diff --git a/builtins/builtins_test.go b/builtins/builtins_test.go
@@ -39,6 +39,67 @@ func TestArch(t *testing.T) {
 	}
 }
 
+// Test (base
+func TestBase(t *testing.T) {
+
+	// No arguments
+	out := baseFn(ENV, []primitive.Primitive{})
+
+	// Will lead to an error
+	e, ok := out.(primitive.Error)
+	if !ok {
+		t.Fatalf("expected error, got %v", out)
+	}
+	if e != primitive.ArityError() {
+		t.Fatalf("got error, but wrong one %v", out)
+	}
+
+	// Arguments must be numbers
+	out = baseFn(ENV, []primitive.Primitive{
+		primitive.Number(3),
+		primitive.String("foo"),
+	})
+
+	// Will lead to an error
+	e, ok = out.(primitive.Error)
+	if !ok {
+		t.Fatalf("expected error, got %v", out)
+	}
+	if !strings.Contains(string(e), "not a number") {
+		t.Fatalf("got error, but wrong one %v", out)
+	}
+
+	// Arguments must be numbers
+	out = baseFn(ENV, []primitive.Primitive{
+		primitive.String("foo"),
+		primitive.Number(3),
+	})
+
+	// Will lead to an error
+	e, ok = out.(primitive.Error)
+	if !ok {
+		t.Fatalf("expected error, got %v", out)
+	}
+	if !strings.Contains(string(e), "not a number") {
+		t.Fatalf("got error, but wrong one %v", out)
+	}
+
+	// Valid result
+	result := baseFn(ENV, []primitive.Primitive{
+		primitive.Number(255),
+		primitive.Number(2),
+	})
+
+	// Will lead to an error
+	r, ok2 := result.(primitive.String)
+	if !ok2 {
+		t.Fatalf("expected string, got %v", result)
+	}
+	if !strings.Contains(string(r), "11111111") {
+		t.Fatalf("got string, but wrong one %v", r)
+	}
+}
+
 // Test (car
 func TestCar(t *testing.T) {
 
@@ -2561,7 +2622,6 @@ func TestNth(t *testing.T) {
 	// No arguments
 	out := nthFn(ENV, []primitive.Primitive{})
 
-
 	// Will lead to an error
 	e, ok := out.(primitive.Error)
 	if !ok {
@@ -2587,7 +2647,6 @@ func TestNth(t *testing.T) {
 		t.Fatalf("got error, but wrong one %v", out)
 	}
 
-
 	// Not a number
 	out = nthFn(ENV, []primitive.Primitive{
 		primitive.List{},
@@ -2602,13 +2661,11 @@ func TestNth(t *testing.T) {
 		t.Fatalf("got error, but wrong one %v", out)
 	}
 
-
 	// bound checking
 	var l primitive.List
 	l = append(l, primitive.String("one"))
 	l = append(l, primitive.String("two"))
 
-
 	// negative offset
 	out = nthFn(ENV, []primitive.Primitive{
 		l,
@@ -2639,7 +2696,6 @@ func TestNth(t *testing.T) {
 		t.Fatalf("got error, but wrong one %v", out)
 	}
 
-
 	// valid access
 	str := nthFn(ENV, []primitive.Primitive{
 		l,
@@ -2670,6 +2726,78 @@ func TestNth(t *testing.T) {
 
 }
 
+func TestNumber(t *testing.T) {
+
+	// No arguments
+	out := numberFn(ENV, []primitive.Primitive{})
+
+	// Will lead to an error
+	e, ok := out.(primitive.Error)
+	if !ok {
+		t.Fatalf("expected error, got %v", out)
+	}
+	if e != primitive.ArityError() {
+		t.Fatalf("got error, but wrong one:%s", out)
+	}
+
+	// Must be a string.
+	out = numberFn(ENV, []primitive.Primitive{
+		primitive.Number(3),
+	})
+
+	// Will lead to an error
+	e, ok = out.(primitive.Error)
+	if !ok {
+		t.Fatalf("expected error, got %v", out)
+	}
+	if !strings.Contains(string(e), "not a string") {
+		t.Fatalf("got error, but wrong one %v", out)
+	}
+
+	// Type for table-driven tests
+	type Input struct {
+		Inp string
+		Out int
+	}
+
+	// Trivial test-cases with base10, base2, and base16
+	tests := []Input{
+		Input{"3", 3},
+		Input{"0b1111", 15},
+		Input{"0xff", 255},
+	}
+
+	for _, tst := range tests {
+
+		res := numberFn(ENV, []primitive.Primitive{
+			primitive.String(tst.Inp),
+		})
+
+		// Will lead to a number
+		r, ok2 := res.(primitive.Number)
+		if !ok2 {
+			t.Fatalf("expected number, got %v", res)
+		}
+		if int(r) != tst.Out {
+			t.Fatalf("got %d, not %d", int(r), tst.Out)
+		}
+	}
+
+	// Failure to convert a bogus number
+	out = numberFn(ENV, []primitive.Primitive{
+		primitive.String("3.3.3.3"),
+	})
+
+	// Will lead to an error
+	e, ok = out.(primitive.Error)
+	if !ok {
+		t.Fatalf("expected error, got %v", out)
+	}
+	if !strings.Contains(string(e), "failed to convert") {
+		t.Fatalf("got error, but wrong one %v", out)
+	}
+}
+
 func TestOrd(t *testing.T) {
 
 	// no arguments

diff --git a/builtins/help.txt b/builtins/help.txt
@@ -43,6 +43,15 @@ arch returns a simple string describing the architecture the current host is run
 See also: (os)
 Example : (print (arch))
 %%
+base
+
+Convert the given number into a string representation in the specified base.
+
+See also: number, sprintf, str
+
+Example: (print (base 255 2))  ; base two is binary
+Example: (print (base 255 16)) ; base 16 is hexadecimal
+%%
 car
 car returns the first item from the specified list.
 %%
@@ -241,6 +250,16 @@ NOTE: The offset starts from 0, to access the first item.
 
 Example: (print (nth '( 1 2 3 ) 0 ) )
 %%
+number
+
+Number will convert the given string to a number object, and supports
+hexadecimal, binary, and base-ten values.
+
+Example: (print (number "0xffed"))
+Example: (print (number "0b1011"))
+
+See also: base, str
+%%
 ord
 
 ord returns the ASCII code for the character provided as the first input.
@@ -329,10 +348,14 @@ When a format string is used it can contain the following strings:
 
 See also: print
 Example: (sprintf "Today is %s" (weekday))
+Example: (sprintf "31 in binary is %08b" 31)
 %%
 str
 
 str converts the parameter supplied to a string, and returns it.
+
+Example: (print (str 3))
+See also: base, number
 %%
 time