feat: Allow Parameters to be Bare Array of Items

Parameters may now be both Bare Items and Bare Array of Item (effectively an unparameterized InnerList).

This implements the proposal in httpwg/http-extensions#2732 that effectively allows nesting of parameters.

package.json

@@ -1,6 +1,6 @@
 {
-  "name": "structured-headers",
-  "version": "2.0.0-alpha.1",
+  "name": "@cxres/structured-headers",
+  "version": "2.0.0-alpha.1-nesting.0",
   "description": "Implementation of RFC8941, structured headers for HTTP.",
   "type": "module",
   "exports": "./dist/index.js",

src/parser.ts

@@ -132,7 +132,17 @@ export default class Parser {
 
   }
 
-  private parseInnerList(): InnerList {
+  private parseBareItemOrBareItemArray(): BareItem|Item[] {
+
+    if (this.lookChar()==='(') {
+      return this.parseBareItemArray();
+    } else {
+      return this.parseBareItem();
+    }
+
+  }
+
+  private parseBareItemArray(): Item[] {
 
     this.expectChar('(');
     this.pos++;
@@ -143,10 +153,7 @@ export default class Parser {
       this.skipWS();
       if (this.lookChar() === ')') {
         this.pos++;
-        return [
-          innerList,
-          this.parseParameters()
-        ];
+        return innerList;
       }
 
       innerList.push(this.parseItem(false));
@@ -162,6 +169,15 @@ export default class Parser {
 
   }
 
+  private parseInnerList(): InnerList {
+
+    return [
+      this.parseBareItemArray(),
+      this.parseParameters()
+    ];
+
+  }
+
   private parseBareItem(): BareItem {
 
     const char = this.lookChar();
@@ -204,10 +220,10 @@ export default class Parser {
       this.pos++;
       this.skipWS();
       const key = this.parseKey();
-      let value: BareItem = true;
+      let value: BareItem|Item[] = true;
       if (this.lookChar() === '=') {
         this.pos++;
-        value = this.parseBareItem();
+        value = this.parseBareItemOrBareItemArray();
       }
       parameters.set(key, value);
     }

src/serializer.ts

@@ -80,10 +80,12 @@ export function serializeItem(input: Item|BareItem, params?: Parameters): string
 
 }
 
-export function serializeInnerList(input: InnerList): string {
-
-  return `(${input[0].map(value => serializeItem(value)).join(' ')})${serializeParameters(input[1])}`;
+export function serializeBareItemArray(input: Item[]): string {
+  return `(${input.map(value => serializeItem(value)).join(' ')})`;
+}
 
+export function serializeInnerList(input: InnerList): string {
+  return `${serializeBareItemArray(input[0])}${serializeParameters(input[1])}`;
 }
 
 
@@ -180,7 +182,11 @@ export function serializeParameters(input: Parameters): string {
 
     let out = ';' + serializeKey(key);
     if (value!==true) {
-      out+='=' + serializeBareItem(value);
+      if (Array.isArray(value)) {
+        out+='=' + serializeBareItemArray(value);
+      } else {
+        out+='=' + serializeBareItem(value);
+      }
     }
     return out;
 

src/types.ts

@@ -19,7 +19,7 @@ export type InnerList = [Item[], Parameters];
  * Parameters they occur within, and the values are bare items (i.e., they
  * themselves cannot be parameterized
  */
-export type Parameters = Map<string, BareItem>;
+export type Parameters = Map<string, BareItem|Item[]>;
 
 /**
  * Dictionaries are ordered maps of key-value pairs, where the keys are short