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Change parser output to String.

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This commit is contained in:
Stephen Chung
2020-10-27 09:56:37 +08:00
parent 54d68c1061
commit 4add90b215
4 changed files with 63 additions and 64 deletions
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48
doc/src/engine/custom-syntax.md
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@@ -116,16 +116,19 @@ The function signature of an implementation is:
where:
* `context: &mut EvalContext` - mutable reference to the current evaluation _context_, exposing the following:
* `context.scope: &mut Scope` - mutable reference to the current [`Scope`]; variables can be added to/removed from it.
* `context.engine(): &Engine` - reference to the current [`Engine`].
* `context.iter_namespaces(): impl Iterator<Item = &Module>` - iterator of the namespaces (as [modules]) containing all script-defined functions.
* `context.this_ptr(): Option<&Dynamic>` - reference to the current bound [`this`] pointer, if any.
* `context.call_level(): usize` - the current nesting level of function calls.
| Parameter | Type | Description |
| ----------------------------- | :-----------------------------: | ------------------------------------------------------------------------------------- |
| `context` | `&mut EvalContext` | mutable reference to the current evaluation _context_ |
| - `context.scope` | `&mut Scope` | mutable reference to the current [`Scope`]; variables can be added to/removed from it |
| - `context.engine()` | `&Engine` | reference to the current [`Engine`] |
| - `context.iter_namespaces()` | `impl Iterator<Item = &Module>` | iterator of the namespaces (as [modules]) containing all script-defined functions |
| - `context.this_ptr()` | `Option<&Dynamic>` | reference to the current bound [`this`] pointer, if any |
| - `context.call_level()` | `usize` | the current nesting level of function calls |
| `inputs` | `&[Expression]` | a list of input expression trees |
* `inputs: &[Expression]` - a list of input expression trees.
### Return Value
* Return value - result of evaluating the custom syntax expression.
Return value is the result of evaluating the custom syntax expression.
### Access Arguments
@@ -283,12 +286,12 @@ engine.register_custom_syntax_raw(
"perform",
|stream| match stream.len() {
// perform ...
1 => Ok(Some("$ident$".into())),
1 => Ok(Some("$ident$".to_string())),
// perform command ...
2 => match stream[1].as_str() {
"action" => Ok(Some("$expr$".into())),
"hello" => Ok(Some("world".into())),
"update" | "check" | "add" | "remove" => Ok(Some("$ident$".into())),
"action" => Ok(Some("$expr$".to_string())),
"hello" => Ok(Some("world".to_string())),
"update" | "check" | "add" | "remove" => Ok(Some("$ident$".to_string())),
"cleanup" => Ok(None),
cmd => Err(ParseError(Box::new(ParseErrorType::BadInput(
format!("Improper command: {}", cmd))),
@@ -320,21 +323,20 @@ engine.register_custom_syntax_raw(
The custom syntax parser has the following signature:
> `Fn(stream: &[String]) -> Result<Option<ImmutableString>, ParseError>`
> `Fn(stream: &[String]) -> Result<Option<String>, ParseError>`
where:
* `stream: &[String]` - a slice of symbols that have been parsed so far, perhaps containing the following:
* `$expr$` - an expression
* `$block$` - a statement block
| Parameter | Type | Description |
| --------- | :---------: | -------------------------------------------------------------------------------------------------- |
| `stream` | `&[String]` | a slice of symbols that have been parsed so far, possibly containing `"$expr$"` and/or `"$block$"` |
### Return Value
The return value is `Result<Option<ImmutableString>, ParseError>` where:
The return value is `Result<Option<String>, ParseError>` where:
* `Ok(None)` - parsing complete and there are no more symbols to match.
* `Ok(Some(symbol))` - next symbol to match.
* `Err(ParseError)` - error is reflected back to the [`Engine`].
Normally this is `ParseErrorType::BadInput` to indicate that there is a syntax error, but it can be any error.
| Value | Description |
| ------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `Ok(None)` | parsing complete and there are no more symbols to match |
| `Ok(Some(symbol))` | next symbol to match, which can also be `"$expr$"`, `"$ident$"` or `"$block$"` |
| `Err(ParseError)` | error that is reflected back to the [`Engine`].<br/>Normally this is `ParseError(ParseErrorType::BadInput(message), Position::none())` to indicate that there is a syntax error, but it can be any `ParseError`. |