Getting the left and right sides.

js/test_cases/helpers_eq/README.md

@@ -0,0 +1,5 @@
+Without a key parameter, neither the main block nor the else block is rendered.
+
+Without a value parameter, it probably uses "null" but I haven't yet confirmed that with additional testing. Potentially could also just be making all falsey values equal.
+
+Literal values work in both keys and values.

js/test_cases/helpers_eq/main.dust

@@ -8,3 +8,8 @@ beta is {beta}{~n}
 {@eq key=int value="7"}int is equal to "7"{:else}int does not equal "7"{/eq}{~n}
 {@eq key=int value=7}int is equal to 7{:else}int does not equal 7{/eq}{~n}
 {@eq key=alpha value=beta}alpha is equal to beta{:else}alpha does not equal beta{/eq}{~n}
+{@eq value=beta}missing key is true{:else}missing key is false{/eq}{~n}
+{@eq value=gamma}missing key and non-existent value is true{:else}missing key and non-existent value is false{/eq}{~n}
+{@eq key=alpha}missing value is true{:else}missing value is false{/eq}{~n}
+{@eq key=gamma}missing value and non-existent key is true{:else}missing value and non-existent key is false{/eq}{~n}
+{@eq key="master" value="master"}"master" is equal to "master"{:else}"master" does not equal "master"{/eq}{~n}

src/parser/parser.rs

@@ -106,10 +106,10 @@ pub struct NamedBlock<'a> {
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct ParameterizedBlock<'a> {
-    name: &'a str,
+    pub name: &'a str,
-    params: Vec<KVPair<'a>>,
+    pub params: Vec<KVPair<'a>>,
-    contents: Option<Body<'a>>,
+    pub contents: Option<Body<'a>>,
-    else_contents: Option<Body<'a>>,
+    pub else_contents: Option<Body<'a>>,
 }
 
 #[derive(Clone, Debug, PartialEq)]

src/renderer/renderer.rs

@@ -1,6 +1,8 @@
 use crate::parser::template;
 use crate::parser::Body;
 use crate::parser::DustTag;
+use crate::parser::KVPair;
+use crate::parser::RValue;
 use crate::parser::Special;
 use crate::parser::Template;
 use crate::parser::TemplateElement;
@@ -222,6 +224,28 @@ impl<'a> DustRenderer<'a> {
                     },
                 };
             }
+            DustTag::DTHelperEquals(parameterized_block) => {
+                let param_map: HashMap<&'a str, &'a RValue<'a>> = parameterized_block
+                    .params
+                    .iter()
+                    .map(|pair: &KVPair<'a>| (pair.key, &pair.value))
+                    .collect();
+                let left_side: Result<&dyn ContextElement, WalkError> = match param_map.get("key") {
+                    None => return Ok("".to_owned()),
+                    Some(rval) => match rval {
+                        RValue::RVString(text) => Ok(text),
+                        RValue::RVPath(path) => walk_path(breadcrumbs, &path.keys),
+                    },
+                };
+                let right_side: Result<&dyn ContextElement, WalkError> =
+                    match param_map.get("value") {
+                        None => Err(WalkError::CantWalk),
+                        Some(rval) => match rval {
+                            RValue::RVString(text) => Ok(text),
+                            RValue::RVPath(path) => walk_path(breadcrumbs, &path.keys),
+                        },
+                    };
+            }
             _ => (), // TODO: Implement the rest
         }
         Ok("".to_owned())