Function __installFunction

sqlite-wasm-cos/sqlite3-node.mjs:7700–7756

(func, sig, scoped)

     is not stashed there.
  */
  const __installFunction = function f(func, sig, scoped){
    if(scoped && !cache.scopedAlloc.length){
      toss("No scopedAllocPush() scope is active.");
    }
    if('string'===typeof func){
      const x = sig;
      sig = func;
      func = x;
    }
    if('string'!==typeof sig || !(func instanceof Function)){
      toss("Invalid arguments: expecting (function,signature) "+
           "or (signature,function).");
    }
    const ft = target.functionTable();
    const oldLen = __asPtrType(ft.length);
    let ptr;
    while( (ptr = cache.freeFuncIndexes.pop()) ){
      if(ft.get(ptr)){
        /* freeFuncIndexes's entry is stale. Table was modified via a
           different API */
        ptr = null;
        continue;
      }else{
        /* This index is free. We'll re-use it. */
        break;
      }
    }
    if(!ptr){
      ptr = __asPtrType(oldLen);
      ft.grow(__asPtrType(1));
    }
    try{
      /*this will only work if func is a WASM-exported function*/
      ft.set(ptr, func);
      if(scoped){
        cache.scopedAlloc.pushPtr(ptr);
      }
      return ptr;
    }catch(e){
      if(!(e instanceof TypeError)){
        if(ptr===oldLen) cache.freeFuncIndexes.push(oldLen);
        throw e;
      }
    }
    // It's not a WASM-exported function, so compile one...
    try {
      const fptr = target.jsFuncToWasm(func, sig);
      ft.set(ptr, fptr);
      if(scoped){
        cache.scopedAlloc.pushPtr(ptr);
      }
    }catch(e){
      if(ptr===oldLen) cache.freeFuncIndexes.push(oldLen);
      throw e;
    }
    return ptr;
  };