Comments (1)
It would certainly be possible for the macro to insert a call to a whitespace()
rule between each and every concatenated expression. But then you need a way to turn it off for specific rules or subexpressions, because you don't want to allow whitespace in the middle of the lexer-style rules (e.g. between the characters of an identifier). You also need a way to specify where whitespace is required vs optional. The rust-peg syntax for calling the _
, __
, and ___
rules with minimal syntax is designed to make this as easy as possible with the normal semantics of rules.
Pest has this feature, but pest requires the ~
operator for concatenation, while in rust-peg you just put expressions next to each other with no operator. So you could equivalently say that _
is the rust-peg concatenation operator when you want to allow whitespace and end up with the same number of characters in the grammar as pest. That avoids all the complexity of trying to auto-insert calls to a whitespace rule, and makes it completely explicit.
That seems good enough to me, but if you have a concrete proposal I'd be happy to hear it.
from rust-peg.
Related Issues (20)
- feature request: a way to query the current line number during parsing HOT 5
- general question about thread safety HOT 1
- Use tracing rather than println?
- Binding captured strings? HOT 6
- help with misleading expected set HOT 2
- How do I escape the dot character in [^ pat]? HOT 1
- rustc warning about unused imports HOT 1
- Make the TokenStream wrappers used internally available
- How to escape the " HOT 3
- Mutual recursion with `#[cache_left_rec]` fails
- Case-insensitive literal matches throw off error position HOT 6
- `{? Err("x") }` should not be considered nullable for infinite loop check
- the `#[proc_macro]` attribute is only usable with crates of the `proc-macro` crate type HOT 2
- "rule" but not when HOT 2
- Error recovery when using `precedence!` HOT 2
- What about presenting on Rust Ukraine Conference 2024?
- feat: in rule where clauses support
- feat: mut variable syntax support for TaggedExpr and RuleParam HOT 2
- Improve error prompt information when there is insufficient input HOT 1
Recommend Projects
-
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
-
Vue.js
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
-
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
-
TensorFlow
An Open Source Machine Learning Framework for Everyone
-
Django
The Web framework for perfectionists with deadlines.
-
Laravel
A PHP framework for web artisans
-
D3
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
-
Recommend Topics
-
javascript
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
-
web
Some thing interesting about web. New door for the world.
-
server
A server is a program made to process requests and deliver data to clients.
-
Machine learning
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
-
Visualization
Some thing interesting about visualization, use data art
-
Game
Some thing interesting about game, make everyone happy.
Recommend Org
-
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
-
Microsoft
Open source projects and samples from Microsoft.
-
Google
Google ❤️ Open Source for everyone.
-
Alibaba
Alibaba Open Source for everyone
-
D3
Data-Driven Documents codes.
-
Tencent
China tencent open source team.
from rust-peg.