From f469097e8bb7280ec76f9ed4ce36c2eb6a05560a Mon Sep 17 00:00:00 2001
From: Ben Johnson <benbjohnson@yahoo.com>
Date: Thu, 11 Dec 2014 09:58:33 -0700
Subject: [PATCH] Add ability to fold without now().

---
 influxql/ast.go         |  8 ++++----
 influxql/ast_test.go    | 18 ++++++++++--------
 influxql/parser_test.go |  9 +++++++++
 3 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/influxql/ast.go b/influxql/ast.go
index 592210f767..eb7cbe0e68 100644
--- a/influxql/ast.go
+++ b/influxql/ast.go
@@ -577,12 +577,12 @@ func (e *Wildcard) String() string { return "*" }
 
 // Fold performs constant folding on an expression.
 // The function, "now()", is expanded into the current time during folding.
-func Fold(expr Expr, now time.Time) Expr {
+func Fold(expr Expr, now *time.Time) Expr {
 	switch expr := expr.(type) {
 	case *Call:
 		// Replace "now()" with current time.
-		if strings.ToLower(expr.Name) == "now" {
-			return &TimeLiteral{Val: now}
+		if strings.ToLower(expr.Name) == "now" && now != nil {
+			return &TimeLiteral{Val: *now}
 		}
 
 		// Fold call arguments.
@@ -610,7 +610,7 @@ func Fold(expr Expr, now time.Time) Expr {
 }
 
 // foldBinaryExpr performs constant folding if the binary expression has two literals.
-func foldBinaryExpr(expr *BinaryExpr, now time.Time) Expr {
+func foldBinaryExpr(expr *BinaryExpr, now *time.Time) Expr {
 	// Fold both sides of binary expression first.
 	expr.LHS = Fold(expr.LHS, now)
 	expr.RHS = Fold(expr.RHS, now)
diff --git a/influxql/ast_test.go b/influxql/ast_test.go
index d9eadfd338..aa67945f3f 100644
--- a/influxql/ast_test.go
+++ b/influxql/ast_test.go
@@ -141,15 +141,9 @@ func TestFold(t *testing.T) {
 		// String literals.
 		{`"foo" + 'bar'`, `"foobar"`},
 	} {
-		// Parse incoming expression.
-		expr, err := influxql.NewParser(strings.NewReader(tt.in)).ParseExpr()
-		if err != nil {
-			t.Errorf("%d. %s: parse error: %s", i, tt.in, err)
-			continue
-		}
-
 		// Fold expression.
-		expr = influxql.Fold(expr, mustParseTime("2000-01-01T00:00:00Z"))
+		now := mustParseTime("2000-01-01T00:00:00Z")
+		expr := influxql.Fold(MustParseExpr(tt.in), &now)
 
 		// Compare with expected output.
 		if out := expr.String(); tt.out != out {
@@ -158,3 +152,11 @@ func TestFold(t *testing.T) {
 		}
 	}
 }
+
+// Ensure an a "now()" call is not folded when now is not passed in.
+func TestFold_WithoutNow(t *testing.T) {
+	expr := influxql.Fold(MustParseExpr(`now()`), nil)
+	if s := expr.String(); s != `now()` {
+		t.Fatalf("unexpected expr: %s", s)
+	}
+}
diff --git a/influxql/parser_test.go b/influxql/parser_test.go
index 01796d8563..eb58d4136a 100644
--- a/influxql/parser_test.go
+++ b/influxql/parser_test.go
@@ -451,6 +451,15 @@ func MustParseSelectStatement(s string) *influxql.SelectStatement {
 	return stmt.(*influxql.SelectStatement)
 }
 
+// MustParseExpr parses an expression. Panic on error.
+func MustParseExpr(s string) influxql.Expr {
+	expr, err := influxql.NewParser(strings.NewReader(s)).ParseExpr()
+	if err != nil {
+		panic(err.Error())
+	}
+	return expr
+}
+
 // errstring converts an error to its string representation.
 func errstring(err error) string {
 	if err != nil {