29 lines
948 B
Markdown
29 lines
948 B
Markdown
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Disable Certain Keywords and/or Operators
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========================================
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{{#include ../links.md}}
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For certain embedded usage, it is sometimes necessary to restrict the language to a strict subset of Rhai
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to prevent usage of certain language features.
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Rhai supports surgically disabling a keyword or operator via the `Engine::disable_symbol` method.
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```rust
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use rhai::Engine;
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let mut engine = Engine::new();
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engine.disable_symbol("if"); // disable the 'if' keyword
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engine.disable_symbol("+="); // disable the '+=' operator
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// The following all return parse errors.
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engine.compile("let x = if true { 42 } else { 0 };")?;
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// ^ missing ';' after statement end
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// ^ 'if' is parsed as a variable name
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engine.compile("let x = 40 + 2; x += 1;")?;
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// ^ '+=' is not recognized as an operator
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// ^ other operators are not affected
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```
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