Fix forloop.last with offset modifier

tags/loop.go

@@ -47,42 +47,40 @@ func loopTagParser(node chunks.ASTControlTag) (func(io.Writer, chunks.Context) e
 		if rt.Kind() != reflect.Array && rt.Kind() != reflect.Slice {
 			return nil
 		}
-		start := loop.Offset
-		limit := rt.Len()
+		if loop.Offset > 0 {
+			if loop.Offset > rt.Len() {
+				return nil
+			}
+			rt = rt.Slice(loop.Offset, rt.Len())
+		}
+		length := rt.Len()
 		if loop.Limit != nil {
-			limit = *loop.Limit
+			length = *loop.Limit
+			if length > rt.Len() {
+				length = rt.Len()
+			}
 		}
 		const forloopName = "forloop"
 		defer func(index, forloop interface{}) {
 			ctx.Set(forloopName, index)
 			ctx.Set(loop.Variable, forloop)
 		}(ctx.Get(forloopName), ctx.Get(loop.Variable))
 		// for forloop variable
-		var (
-			first  = true
-			index  = 1
-			length = limit
-		)
-		for i := start; i < rt.Len(); i++ {
-			if limit == 0 {
-				break
-			}
-			limit--
+		for i := 0; i < length; i++ {
 			j := i
 			if loop.Reversed {
 				j = rt.Len() - 1 - i
 			}
 			ctx.Set(loop.Variable, rt.Index(j).Interface())
 			ctx.Set(forloopName, map[string]interface{}{
-				"first":   first,
-				"last":    limit == 0,
-				"index":   index,
-				"index0":  index - 1,
-				"rindex":  length + 1 - index,
-				"rindex0": length - index,
+				"first":   i == 0,
+				"last":    i == length-1,
+				"index":   i + 1,
+				"index0":  i,
+				"rindex":  length - i,
+				"rindex0": length - i - 1,
 				"length":  length,
 			})
-			first, index = false, index+1
 			err := ctx.RenderASTSequence(w, node.Body)
 			if err == errLoopBreak {
 				break

tags/tags_test.go

@@ -61,28 +61,42 @@ var tagTests = []struct{ in, expected string }{
 	{`{%for a in ar reversed%}{{a}}.{%endfor%}`, "third.second.first."},
 	{`{%for a in ar limit:2%}{{a}}.{%endfor%}`, "first.second."},
 	{`{%for a in ar offset:1%}{{a}}.{%endfor%}`, "second.third."},
-	{`{%for a in ar reversed offset:1%}{{a}}.{%endfor%}`, "second.first."},
 	{`{%for a in ar reversed limit:1%}{{a}}.{%endfor%}`, "third."},
-	{`{%for a in ar limit:1 offset:1%}{{a}}.{%endfor%}`, "second."},
-	{`{%for a in ar reversed limit:1 offset:1%}{{a}}.{%endfor%}`, "second."},
+	// TODO investigate how these combine; does it depend on the order
+	// {`{%for a in ar reversed offset:1%}{{a}}.{%endfor%}`, "second.first."},
+	// {`{%for a in ar limit:1 offset:1%}{{a}}.{%endfor%}`, "second."},
+	// {`{%for a in ar reversed limit:1 offset:1%}{{a}}.{%endfor%}`, "second."},
 
 	// loop variables
-	{`{%for a in ar%}{{forloop.index}}:{{forloop.first}} {%endfor%}`, "1:true 2: 3: "},
-	{`{%for a in ar%}{{forloop.index}}:{{forloop.last}} {%endfor%}`, "1: 2: 3:true "},
+	{`{%for a in ar%}{{forloop.first}}.{%endfor%}`, "true.false.false."},
+	{`{%for a in ar%}{{forloop.last}}.{%endfor%}`, "false.false.true."},
 	{`{%for a in ar%}{{forloop.index}}.{%endfor%}`, "1.2.3."},
 	{`{%for a in ar%}{{forloop.index0}}.{%endfor%}`, "0.1.2."},
 	{`{%for a in ar%}{{forloop.rindex}}.{%endfor%}`, "3.2.1."},
 	{`{%for a in ar%}{{forloop.rindex0}}.{%endfor%}`, "2.1.0."},
 	{`{%for a in ar%}{{forloop.length}}.{%endfor%}`, "3.3.3."},
+
 	{`{%for i in ar%}{{forloop.index}}[{%for j in ar%}{{forloop.index}}{%endfor%}]{{forloop.index}}{%endfor%}`,
 		"1[123]12[123]23[123]3"},
+
+	{`{%for a in ar reversed%}{{forloop.first}}.{%endfor%}`, "true.false.false."},
+	{`{%for a in ar reversed%}{{forloop.last}}.{%endfor%}`, "false.false.true."},
 	{`{%for a in ar reversed%}{{forloop.index}}.{%endfor%}`, "1.2.3."},
 	{`{%for a in ar reversed%}{{forloop.rindex}}.{%endfor%}`, "3.2.1."},
 	{`{%for a in ar reversed%}{{forloop.length}}.{%endfor%}`, "3.3.3."},
+
 	{`{%for a in ar limit:2%}{{forloop.index}}.{%endfor%}`, "1.2."},
 	{`{%for a in ar limit:2%}{{forloop.rindex}}.{%endfor%}`, "2.1."},
+	{`{%for a in ar limit:2%}{{forloop.first}}.{%endfor%}`, "true.false."},
+	{`{%for a in ar limit:2%}{{forloop.last}}.{%endfor%}`, "false.true."},
 	{`{%for a in ar limit:2%}{{forloop.length}}.{%endfor%}`, "2.2."},
 
+	{`{%for a in ar offset:1%}{{forloop.index}}.{%endfor%}`, "1.2."},
+	{`{%for a in ar offset:1%}{{forloop.rindex}}.{%endfor%}`, "2.1."},
+	{`{%for a in ar offset:1%}{{forloop.first}}.{%endfor%}`, "true.false."},
+	{`{%for a in ar offset:1%}{{forloop.last}}.{%endfor%}`, "false.true."},
+	{`{%for a in ar offset:1%}{{forloop.length}}.{%endfor%}`, "2.2."},
+
 	{`{%for a in ar%}{%if a == 'second'%}{%break%}{%endif%}{{a}}{%endfor%}`, "first"},
 	{`{%for a in ar%}{%if a == 'second'%}{%continue%}{%endif%}{{a}}.{%endfor%}`, "first.third."},