From e7451defd42009c152bcbb21640295b0d5eda21b Mon Sep 17 00:00:00 2001
From: NikolaLohinski <nikolalohinski@gmail.com>
Date: Sat, 11 May 2024 22:39:06 +0200
Subject: [PATCH] fix(parser): block trimming is broken with consecutive blocks

---
 parser/parser.go                 | 14 +++++++++++++-
 tests/integration/config_test.go | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/parser/parser.go b/parser/parser.go
index 4292afa..f753ea4 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -3,6 +3,7 @@ package parser
 import (
 	"fmt"
 	"io"
+	"regexp"
 	"strings"
 
 	"github.com/nikolalohinski/gonja/v2/config"
@@ -11,6 +12,10 @@ import (
 	"github.com/nikolalohinski/gonja/v2/tokens"
 )
 
+var (
+	lineReturnWithOnlyWitheSpace = regexp.MustCompile("^(\n|\r)[ \t]*$")
+)
+
 type ControlStructureGetter interface {
 	Get(name string) (ControlStructureParser, bool)
 }
@@ -218,7 +223,14 @@ func (p *Parser) parseDocElement() (nodes.Node, error) {
 	case tokens.VariableBegin:
 		return p.ParseExpressionNode()
 	case tokens.BlockBegin:
-		return p.ParseControlStructureBlock()
+		node, err := p.ParseControlStructureBlock()
+		if err != nil {
+			return node, err
+		}
+		if data := p.Current(tokens.Data); data != nil && p.Peek(tokens.BlockBegin) != nil && lineReturnWithOnlyWitheSpace.MatchString(data.Val) {
+			p.Consume() // Consume whitespace
+		}
+		return node, err
 	}
 	return nil, p.Error("Unexpected token (only HTML/tags/filters in templates allowed)", t)
 }
diff --git a/tests/integration/config_test.go b/tests/integration/config_test.go
index 9a0c771..e8c6e69 100644
--- a/tests/integration/config_test.go
+++ b/tests/integration/config_test.go
@@ -268,4 +268,36 @@ var _ = Context("config", func() {
 			})
 		})
 	})
+	Context("https://github.com/NikolaLohinski/gonja/issues/18", func() {
+		BeforeEach(func() {
+			(*configuration).TrimBlocks = true
+			*loader = loaders.MustNewMemoryLoader(map[string]string{
+				*identifier: heredoc.Doc(`
+					{% if one %}
+					- 1
+					{% endif %}
+					{% if two %}
+					- 2
+					{% endif %}
+					{% if three %}
+					- 3
+					{% endif %}`),
+			})
+			(*environment).Context.Set("one", true)
+			(*environment).Context.Set("two", true)
+			(*environment).Context.Set("three", true)
+		})
+
+		It("should return the expected rendered content", func() {
+			By("not returning any error")
+			Expect(*returnedErr).To(BeNil())
+			By("returning the expected result")
+			expected := heredoc.Doc(`
+				- 1
+				- 2
+				- 3
+			`)
+			AssertPrettyDiff(expected, *returnedResult)
+		})
+	})
 })