Change parser output to String.
This commit is contained in:
Stephen Chung
@@ -116,16 +116,19 @@ The function signature of an implementation is:
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where:
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* `context: &mut EvalContext` - mutable reference to the current evaluation _context_, exposing the following:
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* `context.scope: &mut Scope` - mutable reference to the current [`Scope`]; variables can be added to/removed from it.
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* `context.engine(): &Engine` - reference to the current [`Engine`].
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* `context.iter_namespaces(): impl Iterator<Item = &Module>` - iterator of the namespaces (as [modules]) containing all script-defined functions.
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* `context.this_ptr(): Option<&Dynamic>` - reference to the current bound [`this`] pointer, if any.
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* `context.call_level(): usize` - the current nesting level of function calls.
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| Parameter | Type | Description |
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| ----------------------------- | :-----------------------------: | ------------------------------------------------------------------------------------- |
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| `context` | `&mut EvalContext` | mutable reference to the current evaluation _context_ |
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| - `context.scope` | `&mut Scope` | mutable reference to the current [`Scope`]; variables can be added to/removed from it |
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| - `context.engine()` | `&Engine` | reference to the current [`Engine`] |
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| - `context.iter_namespaces()` | `impl Iterator<Item = &Module>` | iterator of the namespaces (as [modules]) containing all script-defined functions |
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| - `context.this_ptr()` | `Option<&Dynamic>` | reference to the current bound [`this`] pointer, if any |
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| - `context.call_level()` | `usize` | the current nesting level of function calls |
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| `inputs` | `&[Expression]` | a list of input expression trees |
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* `inputs: &[Expression]` - a list of input expression trees.
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### Return Value
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* Return value - result of evaluating the custom syntax expression.
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Return value is the result of evaluating the custom syntax expression.
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### Access Arguments
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@@ -283,12 +286,12 @@ engine.register_custom_syntax_raw(
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"perform",
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|stream| match stream.len() {
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// perform ...
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1 => Ok(Some("$ident$".into())),
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1 => Ok(Some("$ident$".to_string())),
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// perform command ...
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2 => match stream[1].as_str() {
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"action" => Ok(Some("$expr$".into())),
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"hello" => Ok(Some("world".into())),
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"update" | "check" | "add" | "remove" => Ok(Some("$ident$".into())),
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"action" => Ok(Some("$expr$".to_string())),
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"hello" => Ok(Some("world".to_string())),
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"update" | "check" | "add" | "remove" => Ok(Some("$ident$".to_string())),
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"cleanup" => Ok(None),
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cmd => Err(ParseError(Box::new(ParseErrorType::BadInput(
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format!("Improper command: {}", cmd))),
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@@ -320,21 +323,20 @@ engine.register_custom_syntax_raw(
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The custom syntax parser has the following signature:
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> `Fn(stream: &[String]) -> Result<Option<ImmutableString>, ParseError>`
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> `Fn(stream: &[String]) -> Result<Option<String>, ParseError>`
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where:
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* `stream: &[String]` - a slice of symbols that have been parsed so far, perhaps containing the following:
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* `$expr$` - an expression
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* `$block$` - a statement block
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| Parameter | Type | Description |
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| --------- | :---------: | -------------------------------------------------------------------------------------------------- |
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| `stream` | `&[String]` | a slice of symbols that have been parsed so far, possibly containing `"$expr$"` and/or `"$block$"` |
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### Return Value
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The return value is `Result<Option<ImmutableString>, ParseError>` where:
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The return value is `Result<Option<String>, ParseError>` where:
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* `Ok(None)` - parsing complete and there are no more symbols to match.
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* `Ok(Some(symbol))` - next symbol to match.
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* `Err(ParseError)` - error is reflected back to the [`Engine`].
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Normally this is `ParseErrorType::BadInput` to indicate that there is a syntax error, but it can be any error.
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| Value | Description |
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| ------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
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| `Ok(None)` | parsing complete and there are no more symbols to match |
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| `Ok(Some(symbol))` | next symbol to match, which can also be `"$expr$"`, `"$ident$"` or `"$block$"` |
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| `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`. |
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@@ -67,27 +67,23 @@ The function signature passed to `Engine::on_var` takes the following form:
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where:
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* `name: &str` - variable name.
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* `index: usize` - an offset from the bottom of the current [`Scope`] that the variable is supposed to reside.
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Offsets start from 1, with 1 meaning the last variable in the current [`Scope`]. Essentially the correct variable is at position `scope.len() - index`.
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If `index` is zero, then there is no pre-calculated offset position and a search through the current [`Scope`] must be performed.
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* `context: &EvalContext` - reference to the current evaluation _context_, which exposes the following fields:
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* `context.scope: &Scope` - reference to the current [`Scope`] containing all variables up to the current evaluation position.
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* `context.engine(): &Engine` - reference to the current [`Engine`].
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* `context.iter_namespaces(): impl Iterator<Item = &Module>` - iterator of the namespaces (as [modules]) containing all script-defined functions.
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* `context.this_ptr(): Option<&Dynamic>` - reference to the current bound [`this`] pointer, if any.
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* `context.call_level(): usize` - the current nesting level of function calls.
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| Parameter | Type | Description |
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| ----------------------------- | :-----------------------------: | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
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| `name` | `&str` | variable name |
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| `index` | `usize` | an offset from the bottom of the current [`Scope`] that the variable is supposed to reside.<br/>Offsets start from 1, with 1 meaning the last variable in the current [`Scope`]. Essentially the correct variable is at position `scope.len() - index`.<br/>If `index` is zero, then there is no pre-calculated offset position and a search through the current [`Scope`] must be performed. |
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| `context` | `&EvalContext` | reference to the current evaluation _context_ |
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| - `context.scope` | `&Scope` | reference to the current [`Scope`] containing all variables up to the current evaluation position |
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| - `context.engine()` | `&Engine` | reference to the current [`Engine`] |
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| - `context.iter_namespaces()` | `impl Iterator<Item = &Module>` | iterator of the namespaces (as [modules]) containing all script-defined functions |
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| - `context.this_ptr()` | `Option<&Dynamic>` | reference to the current bound [`this`] pointer, if any |
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| - `context.call_level()` | `usize` | the current nesting level of function calls |
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### Return Value
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The return value is `Result<Option<Dynamic>, Box<EvalAltResult>>` where:
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* `Ok(None)` - normal variable resolution process should continue, meaning to continue searching through the [`Scope`].
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* `Ok(Some(Dynamic))` - wrapped [`Dynamic`] is taken as the value of the variable, which is treated as a constant.
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* `Err(Box<EvalAltResult>)` - error is reflected back to the [`Engine`].
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Normally this is `EvalAltResult::ErrorVariableNotFound` to indicate that the variable does not exist, but it can be any error.
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| Value | Description |
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| ------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
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| `Ok(None)` | normal variable resolution process should continue, i.e. continue searching through the [`Scope`] |
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| `Ok(Some(Dynamic))` | value of the variable, treated as a constant |
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| `Err(Box<EvalAltResult>)` | error that is reflected back to the [`Engine`].<br/>Normally this is `EvalAltResult::ErrorVariableNotFound(var_name, Position::none())` to indicate that the variable does not exist, but it can be any `EvalAltResult`. |
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