feat: add tags support to formulas

lib/corpus.dart

@@ -22,6 +22,11 @@ class Multimap<K, V> extends DelegatingMap<K, List<V>> {
   }
 }
 
+class FormulaCorpus{
+  final Multimap<String, Formula> _tags = Multimap.create();
+  final Map<String, Formula> _allFormulas = {};
+}
+
 class UnitCorpus {
   final Multimap<String, String> _baseToUnits = Multimap.create();
   final Map<String, UnitSpec> _allUnits = {};

lib/formula_models.dart

@@ -127,6 +127,7 @@ class Formula {
   final List<VariableSpec> input;
   final VariableSpec output;
   final String d4rtCode;
+  final List<String> tags;
 
   Formula({
     required this.name,
@@ -134,6 +135,7 @@ class Formula {
     required this.input,
     required this.output,
     required this.d4rtCode,
+    this.tags = const [],
   }) {
     validate();
   }
@@ -146,7 +148,7 @@ class Formula {
 
   @override
   String toString() =>
-      'Formula(name: $name, description: $description, input: $input, output: $output, d4rtCode: $d4rtCode)';
+      'Formula(name: $name, description: $description, input: $input, output: $output, d4rtCode: $d4rtCode, tags: $tags)';
 
   @override
   bool operator ==(Object other) =>
@@ -157,11 +159,12 @@ class Formula {
           description == other.description &&
           output == other.output &&
           ListEquality().equals(input, other.input) &&
-          d4rtCode == other.d4rtCode;
+          d4rtCode == other.d4rtCode &&
+          ListEquality().equals(tags, other.tags);
 
   @override
   int get hashCode =>
-      Object.hash(name, description, ListEquality().hash(input), output, d4rtCode);
+      Object.hash(name, description, ListEquality().hash(input), output, d4rtCode, ListEquality().hash(tags));
 
   List<String> inputVarNames() =>
       input.map((v) => v.name).toList(growable: false);
@@ -199,6 +202,7 @@ class Formula {
 
     String name = SetUtils.stringValue(theSet, "name");
     String? description = theSet ["description"] as String?;
+    List<String> tags = (theSet["tags"] as List<Object?>? ?? []).map((t) => t.toString()).toList();
     final List<Object?> inputSet = SetUtils.listValue(theSet, "input");
     List<VariableSpec> input = inputSet
         .map((v) => parseVar(v as Map))

lib/formulas.d4rt

@@ -17,7 +17,8 @@ Where:
       {name: "g", unit: "m/s²"}  // Gravitational acceleration
     ],
     output: {name: "h", unit: "m"},  // Height in meters
-    d4rtCode: "h = 0.5 * g * pow(t, 2)"
+    d4rtCode: "h = 0.5 * g * pow(t, 2)",
+    tags: ["physics", "kinematics"]
   },
   
   // Newton's Law of Universal Gravitation
@@ -40,7 +41,8 @@ Where:
       {name: "r", unit: "m"}     // Distance between masses
     ],
     output: {name: "F", unit: "N"},  // Force in newtons
-    d4rtCode: "F = (6.67430e-11 * m1 * m2) / pow(r, 2)"
+    d4rtCode: "F = (6.67430e-11 * m1 * m2) / pow(r, 2)",
+    tags: ["physics", "astronomy", "gravity"]
   },
   
   // Kinetic Energy
@@ -61,7 +63,8 @@ Where:
       {name: "v", unit: "m/s"}  // Velocity
     ],
     output: {name: "KE", unit: "J"},  // Energy in joules
-    d4rtCode: "KE = 0.5 * m * pow(v, 2)"
+    d4rtCode: "KE = 0.5 * m * pow(v, 2)",
+    tags: ["physics", "energy", "mechanics"]
   },
   
   // Projectile Motion Range
@@ -79,7 +82,8 @@ Where:
       {name: "θ", unit: "deg"}   // Launch angle
     ],
     output: {name: "R", unit: "m"},  // Horizontal distance
-    d4rtCode: "R = (pow(v, 2) * sin(2 * radians(θ))) / 9.80665"
+    d4rtCode: "R = (pow(v, 2) * sin(2 * radians(θ))) / 9.80665",
+    tags: ["physics", "kinematics", "projectile"]
   },
 
   {
@@ -99,6 +103,7 @@ Where:
       {name: "a", unit: "m/s²"} // Acceleration
     ],
     output: {name: "F", unit: "N"},  // Force in newtons
-    d4rtCode: "F = m * a"
+    d4rtCode: "F = m * a",
+    tags: ["physics", "mechanics", "newton"]
   },
 ]