refactor: Embed grammar.json

Cargo.toml

@@ -2,4 +2,4 @@
 
 resolver = "2"
 
-members = ["crates/plotnik-cli", "crates/plotnik-lib", "crates/plotnik-langs", "crates/plotnik-macros", "crates/plotnik-core"]
+members = ["crates/plotnik-cli", "crates/plotnik-lib", "crates/plotnik-langs", "crates/plotnik-core"]

crates/plotnik-core/Cargo.toml

@@ -10,5 +10,7 @@ repository = "https://github.com/plotnik-lang/plotnik"
 unexpected_cfgs = { level = "warn", check-cfg = ['cfg(coverage_nightly)'] }
 
 [dependencies]
+indexmap = { version = "2", features = ["serde"] }
+postcard = { version = "1", features = ["alloc"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"

crates/plotnik-core/src/grammar/binary.rs

@@ -0,0 +1,16 @@
+//! Binary serialization for grammars using postcard.
+
+use super::json::GrammarError;
+use super::types::Grammar;
+
+impl Grammar {
+    /// Deserialize grammar from binary format.
+    pub fn from_binary(bytes: &[u8]) -> Result<Self, GrammarError> {
+        postcard::from_bytes(bytes).map_err(GrammarError::Binary)
+    }
+
+    /// Serialize grammar to binary format.
+    pub fn to_binary(&self) -> Vec<u8> {
+        postcard::to_allocvec(self).expect("serialization should not fail")
+    }
+}

crates/plotnik-core/src/grammar/binary_tests.rs

@@ -0,0 +1,39 @@
+use super::*;
+
+#[test]
+fn roundtrip() {
+    let json = r#"{
+        "name": "test",
+        "rules": {
+            "source_file": { "type": "SYMBOL", "name": "expression" },
+            "expression": { "type": "STRING", "value": "x" }
+        }
+    }"#;
+
+    let grammar = Grammar::from_json(json).unwrap();
+    let binary = grammar.to_binary();
+    let decoded = Grammar::from_binary(&binary).unwrap();
+
+    assert_eq!(grammar.name, decoded.name);
+    assert_eq!(grammar.rules.len(), decoded.rules.len());
+}
+
+#[test]
+fn roundtrip_preserves_order() {
+    let json = r#"{
+        "name": "test",
+        "rules": {
+            "program": { "type": "SYMBOL", "name": "statement" },
+            "statement": { "type": "SYMBOL", "name": "expression" },
+            "expression": { "type": "STRING", "value": "x" }
+        }
+    }"#;
+
+    let grammar = Grammar::from_json(json).unwrap();
+    let binary = grammar.to_binary();
+    let decoded = Grammar::from_binary(&binary).unwrap();
+
+    assert_eq!(decoded.rules[0].0, "program");
+    assert_eq!(decoded.rules[1].0, "statement");
+    assert_eq!(decoded.rules[2].0, "expression");
+}