Add bit flag manipulation

go/state/state.go

@@ -27,12 +27,13 @@ type State struct {
 	execPath []string // Command symbols stack
 	arg *string // Optional argument. Nil if not set.
 	sizes map[string]uint16 // Size limits for all loaded symbols.
-	sink *string //
+	sink *string // Sink symbol set for level
+	bitSize uint32 // size of (32-bit capacity) bit flag byte array
 	//sizeIdx uint16
 }
 
 // NewState creates a new State object with bitSize number of error condition states.
-func NewState(bitSize uint64) State {
+func NewState(bitSize uint32) State {
 	if bitSize == 0 {
 		panic("bitsize cannot be 0")
 	} 
@@ -45,11 +46,63 @@ func NewState(bitSize uint64) State {
 		Flags: make([]byte, bitSize / 8),
 		CacheSize: 0,
 		CacheUseSize: 0,
+		bitSize: bitSize,
 	}
 	st.Down("")
 	return st
 }
 
+// SetFlag sets the flag at the given bit field index.
+//
+// Returns true if bit state was changed.
+//
+// Fails if bitindex is out of range.
+func(st *State) SetFlag(bitIndex uint32) (bool, error) {
+	if bitIndex + 1 > st.bitSize {
+		return false, fmt.Errorf("bit index %v is out of range of bitfield size %v", bitIndex, st.bitSize)
+	}
+	r :=st.getFlag(bitIndex)
+	if r {
+		return false, nil
+	}
+	byteIndex := bitIndex / 8
+	localBitIndex := bitIndex % 8
+	b := st.Flags[byteIndex] 
+	st.Flags[byteIndex] = b | (1 << localBitIndex)
+	return true, nil
+}
+
+
+// ResetFlag resets the flag at the given bit field index.
+//
+// Returns true if bit state was changed.
+//
+// Fails if bitindex is out of range.
+func(st *State) ResetFlag(bitIndex uint32) (bool, error) {
+	if bitIndex + 1 > st.bitSize {
+		return false, fmt.Errorf("bit index %v is out of range of bitfield size %v", bitIndex, st.bitSize)
+	}
+	r :=st.getFlag(bitIndex)
+	if !r {
+		return false, nil
+	}
+	byteIndex := bitIndex / 8
+	localBitIndex := bitIndex % 8
+	b := st.Flags[byteIndex] 
+	st.Flags[byteIndex] = b & (^(1 << localBitIndex))
+	return true, nil
+}
+
+// GetFlag returns the state of the flag at the given bit field index.
+//
+// Fails if bit field index is out of range.
+func(st *State) GetFlag(bitIndex uint32) (bool, error) {
+	if bitIndex + 1 > st.bitSize {
+		return false, fmt.Errorf("bit index %v is out of range of bitfield size %v", bitIndex, st.bitSize)
+	}
+	return st.getFlag(bitIndex), nil
+}
+
 // WithCacheSize applies a cumulative cache size limitation for all cached items.
 func(st State) WithCacheSize(cacheSize uint32) State {
 	st.CacheSize = cacheSize
@@ -288,7 +341,16 @@ func(st *State) checkCapacity(v string) uint32 {
 	return sz
 }
 
+// flush relveant properties for level change
 func(st *State) resetCurrent() {
 	st.sink = nil
 	st.CacheMap = make(map[string]string)
 }
+
+// Retrieve the state of a state flag
+func(st *State) getFlag(bitIndex uint32) bool {
+	byteIndex := bitIndex / 8
+	localBitIndex := bitIndex % 8
+	b := st.Flags[byteIndex]
+	return (b & (1 << localBitIndex)) > 0
+}

go/state/state_test.go

@@ -4,8 +4,8 @@ import (
 	"testing"
 )
 
-// Check creation and testing of state flags
-func TestNewStateFlags(t *testing.T) {
+// Check creation 
+func TestNewState(t *testing.T) {
 	st := NewState(5)
 	if len(st.Flags) != 1 {
 		t.Errorf("invalid state flag length: %v", len(st.Flags))
@@ -17,7 +17,73 @@ func TestNewStateFlags(t *testing.T) {
 	st = NewState(17)
 	if len(st.Flags) != 3 {
 		t.Errorf("invalid state flag length: %v", len(st.Flags))
+	}
+}
 
+func TestStateFlags(t *testing.T) {
+	st := NewState(17)
+	v, err := st.GetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if v {
+		t.Errorf("Expected bit 2 not to be set")
+	}
+	v, err = st.SetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Errorf("Expected change to be set for bit 2")
+	}
+	v, err = st.GetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Errorf("Expected bit 2 to be set")
+	}
+	v, err = st.SetFlag(10)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Errorf("Expected change to be set for bit 10")
+	}
+	v, err = st.GetFlag(10)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Errorf("Expected bit 10 to be set")
+	}
+	v, err = st.ResetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Errorf("Expected change to be set for bit 10")
+	}
+	v, err = st.GetFlag(2)
+	if err != nil {
+		t.Error(err)
+	}
+	if v {
+		t.Errorf("Expected bit 2 not to be set")
+	}
+	v, err = st.GetFlag(10)
+	if err != nil {
+		t.Error(err)
+	}
+	if !v {
+		t.Errorf("Expected bit 10 to be set")
+	}
+	v, err = st.SetFlag(10)
+	if err != nil {
+		t.Error(err)
+	}
+	if v {
+		t.Errorf("Expected change not to be set for bit 10")
 	}
 }