VS Code Unity Shader Formatter Bug Fix For Negative Numbers And Exponential Notation

Hey everyone! I wanted to bring up a bug I've encountered while using the vscode-unity-shader-formatter extension. It seems like there's an issue with how the formatter handles negative numbers and exponential notation, leading to some unexpected formatting changes.

The Issue: Spacing Problems with Negative Numbers and Exponential Notation

So, here's the deal. When I use negative numbers or exponential notation in my shader code, the formatter adds extra spaces that I don't want. It's a bit annoying because it makes the code look less clean and consistent. Let's dive deep into the nitty-gritty details,

Understanding the Core Problem

At the heart of this formatting hiccup lies the vscode-unity-shader-formatter's parsing and reformatting logic. It appears that the tool, while generally adept at structuring shader code, struggles with the nuances of numerical representations, especially when negative signs or exponential notations are involved. To truly grasp the issue, we need to dissect how the formatter interprets and manipulates these elements.

The primary challenge seems to stem from the formatter's tokenization process. When the formatter encounters a construct like -1.0 or 1.0e-3, it might be misinterpreting the negative sign or the exponential notation (e-3) as separate tokens that require spacing. This misinterpretation leads to the insertion of spaces where they are syntactically unnecessary and aesthetically displeasing. This is a classic example of a tool applying a general rule (add spaces around operators) too liberally, without considering the specific context of numerical literals.

Moreover, the problem could be exacerbated by the formatter's underlying grammar rules. If the grammar doesn't explicitly account for negative numbers and exponential notation as single, atomic units, the formatter might fall back on more generic rules that mandate spacing around operators. This highlights the importance of a well-defined grammar that accurately reflects the syntax of the shader language and its numerical conventions.

Why This Matters: The Impact on Code Readability and Maintainability

Now, you might be wondering, "Why all the fuss about a few spaces?" Well, in the world of software development, consistency and readability are paramount. Code is not just for machines; it's for humans to read, understand, and maintain. When formatting is inconsistent, it introduces visual clutter that can hinder comprehension and increase the likelihood of errors. In our context, this seemingly minor formatting issue has several far-reaching implications.

Firstly, inconsistent spacing around negative numbers and exponential notations can make the code visually jarring and harder to scan. Developers often rely on visual cues like consistent spacing to quickly identify code elements and understand their relationships. When these cues are disrupted, it slows down the reading process and can lead to misinterpretations. Imagine trying to debug a complex shader with dozens of numerical literals scattered throughout the code, each with slightly different spacing. It's a recipe for headaches and wasted time.

Secondly, this formatting issue can impact the maintainability of the codebase. When code is consistently formatted, it's easier to make changes and ensure that those changes don't introduce unintended side effects. However, when formatting is inconsistent, it becomes more difficult to track changes and identify potential problems. This is especially true in large projects with multiple developers, where a shared coding style is essential for collaboration and code quality.

Lastly, the issue can erode trust in the formatter itself. If a tool consistently produces unexpected or undesirable results, developers might become hesitant to use it, or they might spend extra time manually correcting its output. This defeats the purpose of using a formatter in the first place, which is to automate the formatting process and free up developers to focus on more important tasks. Therefore, addressing this bug is not just about fixing a minor aesthetic issue; it's about ensuring that the formatter remains a reliable and valuable tool in the shader development workflow.

To illustrate, take a look at this example:

Before:

float x = 1.0e-3;
float y = -1.0;

After (with the bug):

float x = 1.0e - 3;
float y = - 1.0;

See those extra spaces? They might seem small, but they add up and make the code look less polished.

Why This Happens: A Closer Look

I'm not entirely sure what's causing this, but my guess is that the formatter might be misinterpreting the - in -1.0 and the - in 1.0e-3 as subtraction operators instead of parts of the number. This leads it to add spaces around them, which is incorrect in this context.

Potential Root Causes and Technical Deep Dive

To truly understand why this bug is occurring, we need to delve into the inner workings of the vscode-unity-shader-formatter. This involves examining its parsing logic, grammar rules, and reformatting algorithms. While I can only speculate without access to the source code, I can outline some potential root causes based on my understanding of similar tools and techniques.

One likely culprit is the formatter's parser, which is responsible for breaking down the shader code into a stream of tokens. If the parser is not correctly identifying negative numbers and exponential notations as single tokens, it might be treating the - sign as a separate subtraction operator. This would trigger the formatter's rule for adding spaces around operators, leading to the unwanted spacing.

The grammar of the formatter also plays a crucial role. The grammar defines the valid syntax of the shader language and how different code elements should be structured. If the grammar doesn't explicitly include rules for negative numbers and exponential notations, the formatter might fall back on more general rules that lead to incorrect formatting. For example, a rule that says "add spaces around all operators" would apply to the - sign in -1.0, even though it's not actually an operator in this context.

Another potential issue is the formatter's reformatting algorithm. This algorithm takes the parsed tokens and rearranges them according to the formatter's rules. If the algorithm doesn't have specific logic for handling negative numbers and exponential notations, it might apply the default spacing rules, resulting in the extra spaces. The algorithm might also be relying on regular expressions or string manipulation techniques that are not robust enough to handle the complexities of numerical literals.

To fix this bug, the developers of the formatter need to carefully examine its parsing logic, grammar, and reformatting algorithm. They might need to add specific rules for handling negative numbers and exponential notations, or they might need to adjust the existing rules to be more context-aware. This could involve updating the parser to correctly identify numerical literals, modifying the grammar to include explicit rules for these constructs, or refining the reformatting algorithm to handle them correctly.

The Importance of Context-Aware Formatting

This bug highlights the importance of context-aware formatting. A good code formatter should not just apply rules blindly; it should understand the context in which those rules are being applied. In the case of negative numbers and exponential notations, the formatter needs to recognize that the - sign is part of the number, not a separate operator. Similarly, it needs to understand that the e-3 in 1.0e-3 is part of the exponential notation, not a sequence of separate tokens.

Achieving context-aware formatting requires a sophisticated parsing and reformatting engine. The formatter needs to be able to analyze the code at a deeper level, taking into account the syntax, semantics, and even the intended meaning of the code. This is a challenging task, but it's essential for creating formatters that produce truly clean and consistent code. By understanding the nuances of the language and the context in which code elements are used, formatters can avoid making mistakes like adding extra spaces around negative numbers and exponential notations.

Steps to Reproduce

Guys, you can easily reproduce this bug by formatting any shader code that includes negative numbers or exponential notation using the vscode-unity-shader-formatter.

1. Open a shader file in VS Code. Make sure you have the vscode-unity-shader-formatter extension installed. I bet you already do!
2. Add some code with negative numbers or exponential notation, like the example above.
3. Use the format document command (usually Shift + Alt + F or Cmd + Shift + P and then type