Under the Hood: GLR Parsing and Disambiguation

Today I want to talk about GLR parsing and the internals of the JS++ parser.

The Problem

In JS++, there is the potential for code to be “ambiguous”. For instance, consider the following example:

Foo<bar> baz;

There are two interpretations for the above statement:

1. A comparison operation: Foo is less than bar is greater than baz.
2. A variable declaration with type Foo<bar> (where Foo is a generic type with type argument bar)

Since JS++ is a superset of the JavaScript programming language, we would naturally expect the first case since JS++ inherited this from JavaScript. However, in order to achieve a concise syntax for generic types, we also need to consider how we can enable the second case.

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