Combined comparison operator <=>, closes #71

``` 1 <=> 0 // 1 0 <=> 0 // 0 -1 <=> 0 // -1 ```
abs-lang · Dec 24, 2018 · ebbf49d · ebbf49d
1 parent 27dfa68
commit ebbf49d
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Showing 5 changed files with 44 additions and 25 deletions.
diff --git a/evaluator/evaluator.go b/evaluator/evaluator.go
@@ -357,6 +357,18 @@ func evalIntegerInfixExpression(
 		return nativeBoolToBooleanObject(leftVal <= rightVal)
 	case ">=":
 		return nativeBoolToBooleanObject(leftVal >= rightVal)
+	case "<=>":
+		i := &object.Integer{}
+
+		if leftVal == rightVal {
+			i.Value = 0
+		} else if leftVal > rightVal {
+			i.Value = 1
+		} else {
+			i.Value = -1
+		}
+
+		return i
 	case "==":
 		return nativeBoolToBooleanObject(leftVal == rightVal)
 	case "!=":

diff --git a/evaluator/evaluator_test.go b/evaluator/evaluator_test.go
@@ -35,6 +35,9 @@ func TestEvalIntegerExpression(t *testing.T) {
 		{"10 && 1", 1},
 		{"0 && 3", 0},
 		{`"hello" && 10`, 10},
+		{"0 <=> 1", -1},
+		{"1 <=> 1", 0},
+		{"2 <=> 1", 1},
 	}
 
 	for _, tt := range tests {

diff --git a/parser/parser.go b/parser/parser.go
@@ -25,27 +25,28 @@ const (
 )
 
 var precedences = map[token.TokenType]int{
-	token.AND:      AND,
-	token.OR:       AND,
-	token.EQ:       EQUALS,
-	token.NOT_EQ:   EQUALS,
-	token.TILDE:    EQUALS,
-	token.IN:       EQUALS,
-	token.COMMA:    EQUALS,
-	token.LT:       LESSGREATER,
-	token.LT_EQ:    LESSGREATER,
-	token.GT:       LESSGREATER,
-	token.GT_EQ:    LESSGREATER,
-	token.PLUS:     SUM,
-	token.MINUS:    SUM,
-	token.SLASH:    PRODUCT,
-	token.ASTERISK: PRODUCT,
-	token.EXPONENT: PRODUCT,
-	token.RANGE:    RANGE,
-	token.LPAREN:   CALL,
-	token.LBRACKET: INDEX,
-	token.DOT:      DOT,
-	token.PIPE:     DOT,
+	token.AND:           AND,
+	token.OR:            AND,
+	token.EQ:            EQUALS,
+	token.NOT_EQ:        EQUALS,
+	token.TILDE:         EQUALS,
+	token.IN:            EQUALS,
+	token.COMMA:         EQUALS,
+	token.LT:            LESSGREATER,
+	token.LT_EQ:         LESSGREATER,
+	token.GT:            LESSGREATER,
+	token.GT_EQ:         LESSGREATER,
+	token.COMBINED_COMP: LESSGREATER,
+	token.PLUS:          SUM,
+	token.MINUS:         SUM,
+	token.SLASH:         PRODUCT,
+	token.ASTERISK:      PRODUCT,
+	token.EXPONENT:      PRODUCT,
+	token.RANGE:         RANGE,
+	token.LPAREN:        CALL,
+	token.LBRACKET:      INDEX,
+	token.DOT:           DOT,
+	token.PIPE:          DOT,
 }
 
 type (
@@ -104,6 +105,7 @@ func New(l *lexer.Lexer) *Parser {
 	p.registerInfix(token.LT_EQ, p.parseInfixExpression)
 	p.registerInfix(token.GT, p.parseInfixExpression)
 	p.registerInfix(token.GT_EQ, p.parseInfixExpression)
+	p.registerInfix(token.COMBINED_COMP, p.parseInfixExpression)
 	p.registerInfix(token.AND, p.parseInfixExpression)
 	p.registerInfix(token.OR, p.parseInfixExpression)
 	p.registerInfix(token.RANGE, p.parseInfixExpression)

diff --git a/parser/parser_test.go b/parser/parser_test.go
@@ -213,6 +213,7 @@ func TestParsingInfixExpressions(t *testing.T) {
 		{"5 ~ 5;", 5, "~", 5},
 		{"5 != 5;", 5, "!=", 5},
 		{"5 ** 5;", 5, "**", 5},
+		{"5 <=> 5;", 5, "<=>", 5},
 		{"foobar + barfoo;", "foobar", "+", "barfoo"},
 		{"foobar - barfoo;", "foobar", "-", "barfoo"},
 		{"foobar * barfoo;", "foobar", "*", "barfoo"},

diff --git a/token/token.go b/token/token.go
@@ -26,10 +26,11 @@ const (
 	AND = "&&"
 	OR  = "OR"
 
-	LT    = "<"
-	LT_EQ = "<="
-	GT    = ">"
-	GT_EQ = ">="
+	LT            = "<"
+	LT_EQ         = "<="
+	GT            = ">"
+	GT_EQ         = ">="
+	COMBINED_COMP = "<=>"
 
 	EQ     = "=="
 	NOT_EQ = "!="