xref: /sqlite-3.40.0/ext/wasm/api/pre-js.js (revision 7e089d0c) 
1/**
2   BEGIN FILE: api/pre-js.js
3
4   This file is intended to be prepended to the sqlite3.js build using
5   Emscripten's --pre-js=THIS_FILE flag (or equivalent).
6*/
7
8// See notes in extern-post-js.js
9const sqlite3InitModuleState = self.sqlite3InitModuleState || Object.create(null);
10delete self.sqlite3InitModuleState;
11
12/**
13   This custom locateFile() tries to figure out where to load `path`
14   from. The intent is to provide a way for foo/bar/X.js loaded from a
15   Worker constructor or importScripts() to be able to resolve
16   foo/bar/X.wasm (in the latter case, with some help):
17
18   1) If URL param named the same as `path` is set, it is returned.
19
20   2) If sqlite3InitModuleState.sqlite3Dir is set, then (thatName + path)
21      is returned (note that it's assumed to end with '/').
22
23   3) If this code is running in the main UI thread AND it was loaded
24      from a SCRIPT tag, the directory part of that URL is used
25      as the prefix. (This form of resolution unfortunately does not
26      function for scripts loaded via importScripts().)
27
28   4) If none of the above apply, (prefix+path) is returned.
29*/
30Module['locateFile'] = function(path, prefix) {
31  let theFile;
32  const up = this.urlParams;
33  if(0){
34    console.warn("locateFile(",arguments[0], ',', arguments[1],")",
35                 'self.location =',self.location,
36                 'sqlite3InitModuleState.scriptDir =',this.scriptDir,
37                 'up.entries() =',Array.from(up.entries()));
38  }
39  if(up.has(path)){
40    theFile = up.get(path);
41  }else if(this.sqlite3Dir){
42    theFile = this.sqlite3Dir + path;
43  }else if(this.scriptDir){
44    theFile = this.scriptDir + path;
45  }else{
46    theFile = prefix + path;
47  }
48  return theFile;
49}.bind(sqlite3InitModuleState);
50
51/**
52   Bug warning: this xInstantiateWasm bit must remain disabled
53   until this bug is resolved or wasmfs won't work:
54
55   https://github.com/emscripten-core/emscripten/issues/17951
56*/
57const xInstantiateWasm = 1
58      ? 'emscripten-bug-17951'
59      : 'instantiateWasm';
60Module[xInstantiateWasm] = function callee(imports,onSuccess){
61  imports.env.foo = function(){};
62  console.warn("instantiateWasm() uri =",callee.uri, self.location.href);
63  const wfetch = ()=>fetch(callee.uri, {credentials: 'same-origin'});
64  const loadWasm = WebAssembly.instantiateStreaming
65        ? async ()=>{
66          return WebAssembly.instantiateStreaming(wfetch(), imports)
67            .then((arg)=>onSuccess(arg.instance, arg.module));
68        }
69        : async ()=>{ // Safari < v15
70          return wfetch()
71            .then(response => response.arrayBuffer())
72            .then(bytes => WebAssembly.instantiate(bytes, imports))
73            .then((arg)=>onSuccess(arg.instance, arg.module));
74        };
75  loadWasm();
76  return {};
77};
78/*
79  It is literally impossible to reliably get the name of _this_ script
80  at runtime, so impossible to derive X.wasm from script name
81  X.js. Thus we need, at build-time, to redefine
82  Module[xInstantiateWasm].uri by appending it to a build-specific
83  copy of this file with the name of the wasm file. This is apparently
84  why Emscripten hard-codes the name of the wasm file into their glue
85  scripts.
86*/
87Module[xInstantiateWasm].uri = 'sqlite3.wasm';
88/* END FILE: api/pre-js.js */
89