[FIX] qweb/component: refactoring of scoping/variables/slots

This commit is a significant refactoring of the internal of QWeb. It
simplifies the way variables/scoping and slots interact together.  The
main idea is that we use a simple scope object instead of a
context/var/scope object.

This commit also implement the actual correct QWeb semantic for the
t-call directive with a sub body.  Before, we simply extracted the
variables from the body and injected them at the top of the sub
template.  We now simply compile the body before the sub template.

This is a joint work with Lucas (lpe).

closes #541
closes #544
closes #545

closes #557
closes #556

src/qweb/compilation_context.ts

@@ -10,35 +10,27 @@ export class CompilationContext {
   code: string[] = [];
   variables: { [key: string]: QWebVar } = {};
   escaping: boolean = false;
-  parentNode: number | null = null;
+  parentNode: number | null | string = null;
   parentTextNode: number | null = null;
   rootNode: number | null = null;
   indentLevel: number = 0;
   rootContext: CompilationContext;
-  caller: Element | undefined;
-  shouldDefineOwner: boolean = false;
   shouldDefineParent: boolean = false;
+  shouldDefineScope: boolean = false;
   shouldDefineQWeb: boolean = false;
   shouldDefineUtils: boolean = false;
   shouldDefineRefs: boolean = false;
   shouldDefineResult: boolean = true;
-  shouldProtectContext: boolean = false;
-  shouldTrackScope: boolean = false;
   loopNumber: number = 0;
   inPreTag: boolean = false;
   templateName: string;
   allowMultipleRoots: boolean = false;
   hasParentWidget: boolean = false;
-  scopeVars: any[] = [];
   currentKey: string = "";
-  templates: { [key: string]: boolean } = {};
-  callingLevel: number = 0;
-  inliningLevel: number = 0;
 
   constructor(name?: string) {
     this.rootContext = this;
     this.templateName = name || "noname";
-    this.templates[this.templateName] = true;
     this.addLine("var h = this.h;");
   }
 
@@ -71,30 +63,16 @@ export class CompilationContext {
   }
 
   generateCode(): string[] {
-    const shouldTrackScope = this.shouldTrackScope && this.scopeVars.length;
-    if (shouldTrackScope) {
-      // add some vars to scope if needed
-      for (let scopeVar of this.scopeVars.reverse()) {
-        let { index, key, indent } = scopeVar;
-        const prefix = new Array(indent + 2).join("    ");
-        this.code.splice(index + 1, 0, prefix + `scope.${key} = context.${key};`);
-      }
-      this.code.unshift("    const scope = Object.create(null);");
-    }
-    if (this.shouldProtectContext) {
-      this.code.unshift("    context = Object.create(context);");
-    }
     if (this.shouldDefineResult) {
       this.code.unshift("    let result;");
     }
+
+    if (this.shouldDefineScope) {
+      this.code.unshift("    let scope = Object.create(context);");
+    }
     if (this.shouldDefineRefs) {
       this.code.unshift("    context.__owl__.refs = context.__owl__.refs || {};");
     }
-    if (this.shouldDefineOwner) {
-      // this is necessary to prevent some directives (t-forach for ex) to
-      // pollute the rendering context by adding some keys in it.
-      this.code.unshift("    let owner = context;");
-    }
     if (this.shouldDefineParent) {
       if (this.hasParentWidget) {
         this.code.unshift("    let parent = extra.parent;");
@@ -131,10 +109,6 @@ export class CompilationContext {
   subContext(key: keyof CompilationContext, value: any): CompilationContext {
     const newContext = Object.create(this);
     newContext[key] = value;
-    if (key === "caller") {
-      newContext.callingLevel++;
-      newContext.inliningLevel++;
-    }
     return newContext;
   }
 
@@ -152,11 +126,6 @@ export class CompilationContext {
     return this.code.length - 1;
   }
 
-  addToScope(key: string, expr: string) {
-    const index = this.addLine(`context.${key} = ${expr};`);
-    this.rootContext.scopeVars.push({ index, key, indent: this.indentLevel });
-  }
-
   addIf(condition: string) {
     this.addLine(`if (${condition}) {`);
     this.indent();
@@ -172,27 +141,6 @@ export class CompilationContext {
     this.dedent();
     this.addLine("}");
   }
-  /**
-   * Recursively (inverse) fetches the `caller` of a context
-   * Useful to determine to which t-call a t-raw="0" refers
-   */
-  getCaller(targetLevel?: number): Element | null {
-    if (targetLevel === undefined) {
-      targetLevel = this.inliningLevel;
-    }
-    if (targetLevel === this.callingLevel) {
-      return this.caller || null;
-    }
-    const proto = (this as any).__proto__;
-    return proto ? proto.getCaller(targetLevel) : null;
-  }
-  /**
-   * Marks the context with the current recursive level
-   * in which we are for inlining archs (t-raw="0")
-   */
-  getInliningContext(): CompilationContext {
-    return this.subContext("inliningLevel", this.inliningLevel - 1);
-  }
 
   getValue(val: any): QWebVar | string {
     return val in this.variables ? this.getValue(this.variables[val]) : val;
@@ -205,6 +153,7 @@ export class CompilationContext {
    * - replace already defined variables by their internal name
    */
   formatExpression(expr: string): string {
+    this.rootContext.shouldDefineScope = true;
     return compileExpr(expr, this.variables);
   }