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Replace - with –

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Stephen Chung
2020-12-29 23:01:34 +08:00
parent a45876856d
commit db5b855dea
51 changed files with 149 additions and 149 deletions
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doc/src/engine/custom-syntax.md
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@@ -33,8 +33,8 @@ Where This Might Be Useful
* Where you just want to confuse your user and make their lives miserable, because you can.
Step One - Design The Syntax
---------------------------
Step One – Design The Syntax
---------------------------------
A custom syntax is simply a list of symbols.
@@ -48,11 +48,11 @@ These symbol types can be used:
* Identifiers following the [variable] naming rules.
* `$expr$` - any valid expression, statement or statement block.
* `$expr$` – any valid expression, statement or statement block.
* `$block$` - any valid statement block (i.e. must be enclosed by `'{'` .. `'}'`).
* `$block$` – any valid statement block (i.e. must be enclosed by `'{'` .. `'}'`).
* `$ident$` - any [variable] name.
* `$ident$` – any [variable] name.
### The First Symbol Must be an Identifier
@@ -103,8 +103,8 @@ print(hello); // variable declared by a custom syntax persists!
```
Step Two - Implementation
-------------------------
Step Two – Implementation
------------------------------
Any custom syntax must include an _implementation_ of it.
@@ -176,8 +176,8 @@ let result = context.eval_expression_tree(expression)?;
```
Step Three - Register the Custom Syntax
--------------------------------------
Step Three – Register the Custom Syntax
--------------------------------------------
Use `Engine::register_custom_syntax` to register a custom syntax.
@@ -244,8 +244,8 @@ exec |x| -> { x += 1 } while x < 0;
```
Step Four - Disable Unneeded Statement Types
-------------------------------------------
Step Four &ndash; Disable Unneeded Statement Types
-------------------------------------------------
When a DSL needs a custom syntax, most likely than not it is extremely specialized.
Therefore, many statement types actually may not make sense under the same usage scenario.
@@ -258,24 +258,24 @@ the scenario.
A keyword or operator that is disabled can still be used in a custom syntax.
In an extreme case, it is possible to disable _every_ keyword in the language, leaving only
custom syntax (plus possibly expressions). But again, Don't Do It™ - unless you are certain
custom syntax (plus possibly expressions). But again, Don't Do It™ &ndash; unless you are certain
of what you're doing.
Step Five - Document
--------------------
Step Five &ndash; Document
-------------------------
For custom syntax, documentation is crucial.
Make sure there are _lots_ of examples for users to follow.
Step Six - Profit!
------------------
Step Six &ndash; Profit!
------------------------
Really Advanced - Custom Parsers
-------------------------------
Really Advanced &ndash; Custom Parsers
-------------------------------------
Sometimes it is desirable to have multiple custom syntax starting with the
same symbol. This is especially common for _command-style_ syntax where the
@@ -395,8 +395,8 @@ Most strings are [`ImmutableString`][string]'s so it is usually more efficient t
The return value is `Result<Option<ImmutableString>, ParseError>` where:
| Value | Description |
| ------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `Ok(None)` | parsing complete and there are no more symbols to match |
| `Ok(Some(symbol))` | the next symbol to match, which can also be `$expr$`, `$ident$` or `$block$` |
| `Err(ParseError)` | error that is reflected back to the [`Engine`] - normally `ParseError(ParseErrorType::BadInput(LexError::ImproperSymbol(message)), Position::NONE)` to indicate that there is a syntax error, but it can be any `ParseError`. |
| Value | Description |
| ------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `Ok(None)` | parsing complete and there are no more symbols to match |
| `Ok(Some(symbol))` | the next symbol to match, which can also be `$expr$`, `$ident$` or `$block$` |
| `Err(ParseError)` | error that is reflected back to the [`Engine`] &ndash; normally `ParseError(ParseErrorType::BadInput(LexError::ImproperSymbol(message)), Position::NONE)` to indicate that there is a syntax error, but it can be any `ParseError`. |