Package path refactor.

operators.go

@@ -0,0 +1,154 @@
+package jet
+
+import "errors"
+
+//----------- Logical operators ---------------//
+
+// Returns a representation of "not expr"
+func NOT(expr BoolExpression) BoolExpression {
+	return newPrefixBoolExpression(expr, "NOT")
+}
+
+//----------- Comparison operators ---------------//
+
+// Returns a representation of "a=b"
+func EQ(lhs, rhs Expression) BoolExpression {
+	return newBinaryBoolExpression(lhs, rhs, "=")
+}
+
+// Returns a representation of "a!=b"
+func NOT_EQ(lhs, rhs Expression) BoolExpression {
+	return newBinaryBoolExpression(lhs, rhs, "!=")
+}
+
+func IS_DISTINCT_FROM(lhs, rhs Expression) BoolExpression {
+	return newBinaryBoolExpression(lhs, rhs, "IS DISTINCT FROM")
+}
+
+func IS_NOT_DISTINCT_FROM(lhs, rhs Expression) BoolExpression {
+	return newBinaryBoolExpression(lhs, rhs, "IS NOT DISTINCT FROM")
+}
+
+// Returns a representation of "a<b"
+func LT(lhs Expression, rhs Expression) BoolExpression {
+	return newBinaryBoolExpression(lhs, rhs, "<")
+}
+
+// Returns a representation of "a<=b"
+func LT_EQ(lhs, rhs Expression) BoolExpression {
+	return newBinaryBoolExpression(lhs, rhs, "<=")
+}
+
+// Returns a representation of "a>b"
+func GT(lhs, rhs Expression) BoolExpression {
+	return newBinaryBoolExpression(lhs, rhs, ">")
+}
+
+// Returns a representation of "a>=b"
+func GT_EQ(lhs, rhs Expression) BoolExpression {
+	return newBinaryBoolExpression(lhs, rhs, ">=")
+}
+
+func EXISTS(subQuery SelectStatement) BoolExpression {
+	return newPrefixBoolExpression(subQuery, "EXISTS")
+}
+
+// --------------- CASE operator -------------------//
+
+type CaseOperatorExpression interface {
+	Expression
+
+	WHEN(condition Expression) CaseOperatorExpression
+	THEN(then Expression) CaseOperatorExpression
+	ELSE(els Expression) CaseOperatorExpression
+}
+
+type caseOperatorImpl struct {
+	expressionInterfaceImpl
+
+	expression Expression
+	when       []Expression
+	then       []Expression
+	els        Expression
+}
+
+func CASE(expression ...Expression) CaseOperatorExpression {
+	caseExp := &caseOperatorImpl{}
+
+	if len(expression) > 0 {
+		caseExp.expression = expression[0]
+	}
+
+	caseExp.expressionInterfaceImpl.parent = caseExp
+
+	return caseExp
+}
+
+func (c *caseOperatorImpl) WHEN(when Expression) CaseOperatorExpression {
+	c.when = append(c.when, when)
+	return c
+}
+
+func (c *caseOperatorImpl) THEN(then Expression) CaseOperatorExpression {
+	c.then = append(c.then, then)
+	return c
+}
+
+func (c *caseOperatorImpl) ELSE(els Expression) CaseOperatorExpression {
+	c.els = els
+
+	return c
+}
+
+func (c *caseOperatorImpl) serialize(statement statementType, out *queryData, options ...serializeOption) error {
+	if c == nil {
+		return errors.New("Case Expression is nil. ")
+	}
+
+	out.writeString("(CASE")
+
+	if c.expression != nil {
+		err := c.expression.serialize(statement, out)
+
+		if err != nil {
+			return err
+		}
+	}
+
+	if len(c.when) == 0 || len(c.then) == 0 {
+		return errors.New("Invalid case Statement. There should be at least one when/then Expression pair. ")
+	}
+
+	if len(c.when) != len(c.then) {
+		return errors.New("When and then Expression count mismatch. ")
+	}
+
+	for i, when := range c.when {
+		out.writeString("WHEN")
+		err := when.serialize(statement, out, NO_WRAP)
+
+		if err != nil {
+			return err
+		}
+
+		out.writeString("THEN")
+		err = c.then[i].serialize(statement, out, NO_WRAP)
+
+		if err != nil {
+			return err
+		}
+	}
+
+	if c.els != nil {
+		out.writeString("ELSE")
+		err := c.els.serialize(statement, out, NO_WRAP)
+
+		if err != nil {
+			return err
+		}
+	}
+
+	out.writeString("END)")
+
+	return nil
+}