bindSourceFile

Basically checks if the file.locals is defined, if not it hands over to (a local function) bind.

TIP: local functions are used heavily within the TypeScript compiler. A local function very likely uses variables from the parent function (captured by closure). In the case of (a local function within bindSourceFile) it (or function it calls) will setup the symbolCount and classifiableNames among others, that are then stored on the returned SourceFile.

bind

bindWorker

This function switches on node.kind (of type SyntaxKind) and delegates work to the appropriate bindFoo function (also defined within binder.ts). For example if the node is a SourceFile it calls (eventually and only if its an external file module) bindAnonymousDeclaration

bindFoo functions

As you can see it is simply keeping the symbolCount (a local to ) up to date and creating the symbol with the specified parameters.