Opt-in trim component definition

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## 2.2.0 (unreleased)
 
 - Do not reserialize existing Value when serializing to a Value
+- Allow trimming start/end of component definition with metadata `{"trim": true}`
 
 ## 2.1.1 (2026-08-11)
 

tera/src/parsing/ast.rs

@@ -755,6 +755,43 @@ impl ComponentDefinition {
         self.kwargs.keys().map(|k| k.as_str()).collect()
     }
 
+    /// Trim body unless the `trim` metadata field is set to `false` or unset
+    pub fn maybe_trim_body(&mut self) {
+        let needs_trimming = self
+            .metadata
+            .get("trim")
+            .and_then(|v| v.as_bool())
+            .unwrap_or(false);
+        if !needs_trimming {
+            return;
+        }
+
+        // We might have multiple Node::Content at start/end if there were comment nodes that got dropped
+        while let Some(Node::Content(c)) = self.body.first_mut() {
+            let t = c.trim_start();
+            if t.is_empty() {
+                self.body.remove(0);
+            } else {
+                if t.len() != c.len() {
+                    *c = t.to_string();
+                }
+                break;
+            }
+        }
+
+        while let Some(Node::Content(c)) = self.body.last_mut() {
+            let t = c.trim_end();
+            if t.is_empty() {
+                self.body.pop();
+            } else {
+                if t.len() != c.len() {
+                    *c = t.to_string();
+                }
+                break;
+            }
+        }
+    }
+
     /// Builds a validated context from provided kwargs, checking types and applying defaults.
     /// If rest_param_name is defined, unknown kwargs are collected into it.
     /// Otherwise, unknown kwargs will error.

tera/src/parsing/parser.rs

@@ -1450,6 +1450,8 @@ impl<'a> Parser<'a> {
         self.body_contexts.pop();
         component_def.body = body;
 
+        component_def.maybe_trim_body();
+
         Ok(component_def)
     }
 

tera/src/snapshot_tests/parser.rs

@@ -56,6 +56,7 @@ fn parser_errors() {
 fn parser_components_definition_success() {
     insta::glob!("parser_inputs/success/components/def/*.txt", |path| {
         let contents = std::fs::read_to_string(path).unwrap();
+        let contents = normalize_line_endings(&contents);
         let components = &Parser::new("", &contents, Delimiters::default())
             .parse()
             .unwrap()
@@ -68,6 +69,7 @@ fn parser_components_definition_success() {
 fn parser_components_render_success() {
     insta::glob!("parser_inputs/success/components/*.txt", |path| {
         let contents = std::fs::read_to_string(path).unwrap();
+        let contents = normalize_line_endings(&contents);
         println!("{path:?}");
         let nodes = &Parser::new("", &contents, Delimiters::default())
             .parse()

tera/src/snapshot_tests/parser_inputs/success/components/def/trim_default.txt

@@ -0,0 +1,3 @@
+{% component greet(label) %}
+{{label}}
+{% endcomponent %}

tera/src/snapshot_tests/parser_inputs/success/components/def/trim_default_with_comment.txt

@@ -0,0 +1,4 @@
+{% component greet(label) %}
+{# this has ws after #}
+{{label}}
+{% endcomponent %}

tera/src/snapshot_tests/parser_inputs/success/components/def/trim_optin.txt

@@ -0,0 +1,3 @@
+{% component greet(label) {"trim": true} %}
+{{label}}
+{% endcomponent %}

tera/src/snapshot_tests/rendering_inputs/success/components/trim_body_def.txt

@@ -0,0 +1,9 @@
+$$ components
+{% component coverlink(dest) {"trim": true} %}
+<a href="{{ dest }}">{{ dest }}</a>
+{% endcomponent coverlink %}
+$$ tpl
+<div>
+{{<coverlink dest="a"/>}}
+{{<coverlink dest="b"/>}}
+</div>

tera/src/snapshot_tests/rendering_inputs/success/components/trim_def_doesnt_touch_body.txt

@@ -0,0 +1,8 @@
+$$ components
+{% component note() {"trim": true} %}
+<aside>{{ body }}</aside>
+{% endcomponent note %}
+$$ tpl
+{% <note> %}
+  hello
+{% </note> %}

tera/src/snapshot_tests/snapshots/tera__snapshot_tests__parser__parser_components_definition_success@trim_default.txt.snap

@@ -0,0 +1,23 @@
+---
+source: tera/src/snapshot_tests/parser.rs
+expression: "components[0]"
+input_file: tera/src/snapshot_tests/parser_inputs/success/components/def/trim_default.txt
+---
+ComponentDefinition {
+    name: "greet",
+    kwargs: {
+        "label": ComponentArgument {
+            default: None,
+            typ: None,
+        },
+    },
+    rest_param_name: None,
+    metadata: {},
+    body: [
+        "\n",
+        Var {
+            name: "label",
+        } @ 2:2-2:7 (31..36),
+        "\n",
+    ],
+}

tera/src/snapshot_tests/snapshots/tera__snapshot_tests__parser__parser_components_definition_success@trim_default_with_comment.txt.snap

@@ -0,0 +1,24 @@
+---
+source: tera/src/snapshot_tests/parser.rs
+expression: "components[0]"
+input_file: tera/src/snapshot_tests/parser_inputs/success/components/def/trim_default_with_comment.txt
+---
+ComponentDefinition {
+    name: "greet",
+    kwargs: {
+        "label": ComponentArgument {
+            default: None,
+            typ: None,
+        },
+    },
+    rest_param_name: None,
+    metadata: {},
+    body: [
+        "\n",
+        "\n",
+        Var {
+            name: "label",
+        } @ 3:2-3:7 (55..60),
+        "\n",
+    ],
+}

tera/src/snapshot_tests/snapshots/tera__snapshot_tests__parser__parser_components_definition_success@trim_optin.txt.snap

@@ -0,0 +1,23 @@
+---
+source: tera/src/snapshot_tests/parser.rs
+expression: "components[0]"
+input_file: tera/src/snapshot_tests/parser_inputs/success/components/def/trim_optin.txt
+---
+ComponentDefinition {
+    name: "greet",
+    kwargs: {
+        "label": ComponentArgument {
+            default: None,
+            typ: None,
+        },
+    },
+    rest_param_name: None,
+    metadata: {
+        "trim": Bool(true),
+    },
+    body: [
+        Var {
+            name: "label",
+        } @ 2:2-2:7 (46..51),
+    ],
+}

tera/src/snapshot_tests/snapshots/tera__snapshot_tests__parser__parser_components_definition_success@trim_optout.txt.snap

@@ -0,0 +1,25 @@
+---
+source: tera/src/snapshot_tests/parser.rs
+expression: "components[0]"
+input_file: tera/src/snapshot_tests/parser_inputs/success/components/def/trim_optout.txt
+---
+ComponentDefinition {
+    name: "greet",
+    kwargs: {
+        "label": ComponentArgument {
+            default: None,
+            typ: None,
+        },
+    },
+    rest_param_name: None,
+    metadata: {
+        "trim": Bool(false),
+    },
+    body: [
+        "\n",
+        Var {
+            name: "label",
+        } @ 2:2-2:7 (47..52),
+        "\n",
+    ],
+}

tera/src/snapshot_tests/snapshots/tera__snapshot_tests__rendering__rendering_components_ok@trim_body_def.txt.snap

@@ -0,0 +1,9 @@
+---
+source: tera/src/snapshot_tests/rendering.rs
+expression: "&out"
+input_file: tera/src/snapshot_tests/rendering_inputs/success/components/trim_body_def.txt
+---
+<div>
+<a href="a">a</a>
+<a href="b">b</a>
+</div>

tera/src/snapshot_tests/snapshots/tera__snapshot_tests__rendering__rendering_components_ok@trim_def_doesnt_touch_body.txt.snap

@@ -0,0 +1,8 @@
+---
+source: tera/src/snapshot_tests/rendering.rs
+expression: "&out"
+input_file: tera/src/snapshot_tests/rendering_inputs/success/components/trim_def_doesnt_touch_body.txt
+---
+<aside>
+  hello
+</aside>

tera/tests/snapshots/basic__rendering_realistic_benchmark.snap

@@ -21,9 +21,7 @@ expression: out
             <a href="https://docs.rs/tera" class="nav-link">API Docs</a>
         </nav>
 
-
-
-<ul>
+        <ul>
 
     <li>1. Hello world</li>
 
@@ -67,7 +65,6 @@ expression: out
 
 </ul>
 
-
 
 
     </div>