Adds an incredibly simple equality operator

3 files changed, 32 insertions, 1 deletions

diff --git a/subex/arithmetic.go b/subex/arithmetic.go
index 9e5e530..4cbc9db 100644
--- a/subex/arithmetic.go
+++ b/subex/arithmetic.go
@@ -156,3 +156,18 @@ func notValues(values walk.ValueList) (notted walk.ValueList, err error) {
 	}
 	return notted, nil
 }
+
+// Returns true if all values are equal, false if not
+func equalValues(values walk.ValueList) (walk.ValueList, error) {
+	if len(values) == 0 {
+		return walk.ValueList{walk.BoolScalar(true)}, nil
+	}
+	first := values[0]
+	for _, value := range values[1:] {
+		// TODO: Refine the equality check
+		if value != first {
+			return walk.ValueList{walk.BoolScalar(false)}, nil
+		}
+	}
+	return walk.ValueList{walk.BoolScalar(true)}, nil
+}
diff --git a/subex/parse.go b/subex/parse.go
index 2392b22..35baaa2 100644
--- a/subex/parse.go
+++ b/subex/parse.go
@@ -260,7 +260,7 @@ func parseSubex(l RuneReader, minPower int, runic bool) SubexAST {
 		// case '[':
 		// 	rangeParts := parseRangeSubex(l)
 		// 	lhs = SubexASTRange {rangeParts}
-		case ')', ']', '"', '|', ';', '{', '+', '-', '*', '/', '!', '$':
+		case ')', ']', '"', '|', ';', '{', '+', '-', '*', '/', '!', '=', '$':
 			l.Rewind()
 			return SubexASTEmpty{}
 		// case '=':
@@ -366,6 +366,8 @@ func parseSubex(l RuneReader, minPower int, runic bool) SubexAST {
 				lhs = SubexASTReciprocal {lhs}
 			case r == '!' && minPower <= 4:
 				lhs = SubexASTNot {lhs}
+			case r == '=' && minPower <= 4:
+				lhs = SubexASTEqual {lhs}
 			case r == '$' && minPower <= 4:
 				slot := l.Next()
 				if slot == eof {
diff --git a/subex/subexast.go b/subex/subexast.go
index b1ac931..e02091d 100644
--- a/subex/subexast.go
+++ b/subex/subexast.go
@@ -395,6 +395,20 @@ func (ast SubexASTNot) String() string {
 	return fmt.Sprintf("(%v)!", ast.Content)
 }
 
+// Runs the content Subex and collects the output
+// Replaces it with true if all output values are equal and false otherwise
+type SubexASTEqual struct {
+	Content SubexAST
+}
+func (ast SubexASTEqual) compileWith(next SubexState, slotMap *SlotMap, runic bool) SubexState {
+	return &SubexCaptureBeginState {
+		next: ast.Content.compileWith(&SubexArithmeticEndState {
+			next: next,
+			calculate: equalValues,
+		}, slotMap, runic),
+	}
+}
+
 // Does nothing
 type SubexASTEmpty struct {}
 func (ast SubexASTEmpty) compileWith(next SubexState, slotMap *SlotMap, runic bool) SubexState {