implmenting caching of matching FunctionDefs in FunctionRef to improv…

…e performance.

src/elm/reusable.ts

@@ -59,27 +59,28 @@ export class FunctionDef extends Expression {
 export class FunctionRef extends Expression {
   name: string;
   library: string;
+  functionDefs: FunctionDef[] | null;
 
   constructor(json: any) {
     super(json);
     this.name = json.name;
     this.library = json.libraryName;
+    this.functionDefs = null;
   }
 
-  async exec(ctx: Context) {
+  getFunctionDefs(ctx: Context, args: any) {
+    if (this.functionDefs != null) {
+      // cache hit
+      return this.functionDefs;
+    }
     let functionDefs, child_ctx;
     if (this.library) {
       const lib = ctx.get(this.library);
       functionDefs = lib ? lib.getFunction(this.name) : undefined;
-      const libCtx = ctx.getLibraryContext(this.library);
-      child_ctx = libCtx ? libCtx.childContext() : undefined;
     } else {
       functionDefs = ctx.get(this.name);
-      child_ctx = ctx.childContext();
     }
-    const args = await this.execArgs(ctx);
 
-    // Filter out functions w/ wrong number of arguments.
     functionDefs = functionDefs.filter((f: any) => f.parameters.length === args.length);
     // If there is still > 1 matching function, filter by argument types
     if (functionDefs.length > 1) {
@@ -101,17 +102,33 @@ export class FunctionRef extends Expression {
         return match;
       });
     }
+    this.functionDefs = functionDefs;
+    return functionDefs;
+  }
+
+  async exec(ctx: Context) {
+    const args = await this.execArgs(ctx);
+    // Filter out functions w/ wrong number of arguments.
+    const fDefs = this.getFunctionDefs(ctx, args);
     // If there is still > 1 matching function, calculate a score based on quality of matches
-    if (functionDefs.length > 1) {
+    if (fDefs.length > 1) {
       // TODO
     }
 
-    if (functionDefs.length === 0) {
+    if (fDefs.length === 0) {
       throw new Error('no function with matching signature could be found');
     }
+
+    let child_ctx;
+    if (this.library) {
+      const libCtx = ctx.getLibraryContext(this.library);
+      child_ctx = libCtx ? libCtx.childContext() : undefined;
+    } else {
+      child_ctx = ctx.childContext();
+    }
     // By this point, we should have only one function, but until implementation is completed,
     // use the last one (no matter how many still remain)
-    const functionDef = functionDefs[functionDefs.length - 1];
+    const functionDef = fDefs[fDefs.length - 1];
     for (let i = 0; i < functionDef.parameters.length; i++) {
       child_ctx.set(functionDef.parameters[i].name, args[i]);
     }