add ability to specify the compiler externally

allows projects which use forks (such as CellEngine) to specify the
compiler module with

require("vue-toolchain/transform").registerCompiler().

for example do it in webpack.config so that by the time webpack calls
the loader it has the right reference to vue-template-compiler

Author: chearon

loader.js

@@ -1,5 +1,5 @@
 const transform = require('./transform');
-const compiler = require('vue-template-compiler'); // just used for logging
+const compiler = transform.compiler || require("vue-template-compiler"); // just used for logging
 
 let SourceMapConsumer, SourceMapGenerator;
 

register.js

@@ -1,6 +1,11 @@
 const transform = require('./transform');
 const jsHook = require.extensions['.js'];
 
+// TODO allow register to be called externally somehow?
+// in CellEngine we need to pass @primitybio/vue-template-compiler,
+// but not a problem right now since we don't use this in CE
+transform.register(require("vue-template-compiler"));
+
 require.extensions['.vue'] = function (module, file) {
   const oldCompile = module._compile;
   module._compile = function (code, file) {

transform.js

@@ -1,6 +1,5 @@
 const babel = require('@babel/core');
 const generate = require('@babel/generator').default;
-const compiler = require('vue-template-compiler');
 const cutils = require('@vue/component-compiler-utils');
 
 function removeSourceMap(ast) {
@@ -86,6 +85,7 @@ const getPlugin = (renderFunctionExpr, staticRenderArrayExpr, isFunctional) => {
 };
 
 module.exports = function (vueSource, vueFilename, extraPlugins) {
+  const compiler = module.exports.compiler || require("vue-template-compiler");
   const plugins = extraPlugins || [];
 
   const {script, template} = cutils.parse({
@@ -122,3 +122,5 @@ module.exports = function (vueSource, vueFilename, extraPlugins) {
     template
   };
 };
+
+module.exports.registerCompiler = c => module.exports.compiler = c;