Delimit package/module names from members

This change removes some ambiguity that existed in MuIL tokens given the
simplistic naming scheme of only using "/" as a delimiter.  We could have
resolved this ambiguity through successive name bindings, but I prefer a
more deterministic approach.  A module member token now delimits the
package/module name from the member name by a ":" character, as in
"aws/ec2:VM".  Furthermore, when reexporting elements from the current
package/module, we will use the self-referential "." character, as in
".:VM".

docs/design/deps.md

@@ -18,7 +18,7 @@ understand how to recognize.  The details of how a language does this is outside
 
 ## References
 
-Each package is referred to using a URL-like scheme, facilitating multiple package management distribution schemes.
+Each package is referenced using a URL-like scheme, facilitating multiple package management distribution schemes.
 For example, the URL `https://hub.mu.com/aws/ec2#^1.0.6` references the `aws/ec2` package on MuHub's built-in package
 manager, and askes specifically for version `1.0.6` or higher using semantic versioning resolution.
 
@@ -37,10 +37,15 @@ Although there are four parts, three of them are optional, because because Mu us
 * `hub.mu.com/` is the default base URL.
 * `latest` is the default version number (a.k.a., "tip").
 
-Although we're concerned with package references right now, we'll see soon that the same reference scheme is also used
+Although we're concerned with package references right now, we'll see soon that a similar reference scheme is used
-to address elements exported from a package, like a module, class, function, or variable.  For example, to reference the
+to address elements exported from a package, like a module, class, function, or variable.  The package plus module uses
-`VM` class from a MuIL token, we might say `https://hub.mu.com/aws/ec2/VM#^1.0.6`.  Most likely, we would leave
+the same grammar as above, however members inside of a module are followed by a `:`.  Furthermore, such references do
-off the protocol, base URL, and version in the token, and leave it to the MuPackage to bind to a specific version.
+not have version numbers.  These references are not strictly URLs and must be interpreted by the Mu toolchain.
+
+For example, to reference the `VM` class from a MuIL token -- assuming we have a dependency declared on
+`https://hub.mu.com/aws/ec2#^1.0.6` as shown above -- we would most likely say `aws/ec2:VM`.  A fully qualified, but
+versionless, reference is also permitted, as in `https://hub.mu.com/aws/ec2:VM`, although this is less conventional.
+Sometimes the self-referential package plus module identifier `.` will be used as a short-hand, as in `.:VM`.
 
 The way these URLs are resolved to physical MuPackages is discussed later on.
 

tools/mujs/lib/compiler/transform.ts

@@ -259,10 +259,13 @@ export class Transformer {
     }
 
     // createModuleMemberToken binds a string-based exported member name to the associated token that references it.
-    private createModuleMemberToken(mod: ModuleReference, name: string): symbols.Token {
+    private createModuleMemberToken(mod: ModuleReference | undefined, name: string): symbols.Token {
         // The concatenated name of the module plus identifier will resolve correctly to an exported definition.
+        if (!mod) {
+            mod = symbols.selfModule;
+        }
         let modtok: symbols.ModuleToken = this.createModuleToken(mod);
-        return `${modtok}${symbols.tokenSep}${name}`;
+        return `${modtok}${symbols.moduleSep}${name}`;
     }
 
     // createModuleReference turns a ECMAScript import path into a MuIL module token.
@@ -515,14 +518,10 @@ export class Transformer {
                     // The export is being renamed (`<propertyName> as <name>`).  This yields an export node, even for
                     // elements exported from the current module.
                     let propertyName: ast.Identifier = this.transformIdentifier(exportClause.propertyName);
-                    let token: symbols.Token = propertyName.ident;
-                    if (sourceModule) {
-                        token = this.createModuleMemberToken(sourceModule, token);
-                    }
                     exports.push(<ast.Export>{
                         kind:  ast.exportKind,
                         name:  name,
-                        token: token,
+                        token: this.createModuleMemberToken(sourceModule, propertyName.ident),
                     });
                 }
                 else {

tools/mujs/lib/symbols/index.ts

@@ -7,7 +7,8 @@ export type TypeToken = Token;     // a symbol token that resolves to a type.
 export type VariableToken = Token; // a symbol token that resolves to a variable.
 export type FunctionToken = Token; // a symbol token that resolves to a function.
 
-export const tokenSep = "/";       // the separator for token "parts" (modules names, etc).
+export const moduleSep = ":";               // a character delimiting module / member names (e.g., "module:member").
+export const selfModule: ModuleToken = "."; // a self-referential token for the current module.
 
 // Accessibility modifiers.
 export type Accessibility            = "public" | "private";        // accessibility modifiers common to all.

tools/mujs/tests/output/modules/reexport/Mu.out.json

@@ -191,7 +191,7 @@
                             }
                         }
                     },
-                    "token": "other/C"
+                    "token": "other:C"
                 },
                 "I": {
                     "kind": "Export",
@@ -210,7 +210,7 @@
                             }
                         }
                     },
-                    "token": "other/I"
+                    "token": "other:I"
                 },
                 "v": {
                     "kind": "Export",
@@ -229,7 +229,7 @@
                             }
                         }
                     },
-                    "token": "other/v"
+                    "token": "other:v"
                 }
             },
             "loc": {

tools/mujs/tests/output/modules/reexport_all/Mu.out.json

@@ -174,29 +174,29 @@
                 "ident": "index"
             },
             "members": {
-                "other/C": {
+                "other:C": {
                     "kind": "Export",
                     "name": {
                         "kind": "Identifier",
-                        "ident": "other/C"
+                        "ident": "other:C"
                     },
-                    "token": "other/C"
+                    "token": "other:C"
                 },
-                "other/I": {
+                "other:I": {
                     "kind": "Export",
                     "name": {
                         "kind": "Identifier",
-                        "ident": "other/I"
+                        "ident": "other:I"
                     },
-                    "token": "other/I"
+                    "token": "other:I"
                 },
-                "other/v": {
+                "other:v": {
                     "kind": "Export",
                     "name": {
                         "kind": "Identifier",
-                        "ident": "other/v"
+                        "ident": "other:v"
                     },
-                    "token": "other/v"
+                    "token": "other:v"
                 }
             },
             "loc": {

tools/mujs/tests/output/modules/reexport_rename/Mu.out.json

@@ -191,7 +191,7 @@
                             }
                         }
                     },
-                    "token": "other/C"
+                    "token": "other:C"
                 },
                 "J": {
                     "kind": "Export",
@@ -210,7 +210,7 @@
                             }
                         }
                     },
-                    "token": "other/I"
+                    "token": "other:I"
                 },
                 "w": {
                     "kind": "Export",
@@ -229,7 +229,7 @@
                             }
                         }
                     },
-                    "token": "other/v"
+                    "token": "other:v"
                 }
             },
             "loc": {