# [−] [src] Struct regex_syntax::ast::parse::ParserBuilder

    pub struct ParserBuilder { /* fields omitted */ }

A builder for a regular expression parser.

This builder permits modifying configuration options for the parser.

## Methods

### `impl ParserBuilder` [src]

#### `pub fn new() -> ParserBuilder` [src]

Create a new parser builder with a default configuration.

#### `pub fn build(&self) -> Parser` [src]

Build a parser from this configuration with the given pattern.

#### `pub fn nest_limit(&mut self, limit: u32) -> &mut ParserBuilder` [src]

Set the nesting limit for this parser.

The nesting limit controls how deep the abstract syntax tree is allowed to be. If the AST exceeds the given limit (e.g., with too many nested groups), then an error is returned by the parser.

The purpose of this limit is to act as a heuristic to prevent stack overflow for consumers that do structural induction on an `Ast` using explicit recursion. While this crate never does this (instead using constant stack space and moving the call stack to the heap), other crates may.

This limit is not checked until the entire Ast is parsed. Therefore, if callers want to put a limit on the amount of heap space used, then they should impose a limit on the length, in bytes, of the concrete pattern string. In particular, this is viable since this parser implementation will limit itself to heap space proportional to the lenth of the pattern string.

Note that a nest limit of `0` will return a nest limit error for most patterns but not all. For example, a nest limit of `0` permits `a` but not `ab`, since `ab` requires a concatenation, which results in a nest depth of `1`. In general, a nest limit is not something that manifests in an obvious way in the concrete syntax, therefore, it should not be used in a granular way.

#### `pub fn octal(&mut self, yes: bool) -> &mut ParserBuilder` [src]

Whether to support octal syntax or not.

Octal syntax is a little-known way of uttering Unicode codepoints in a regular expression. For example, `a`, `\x61`, `\u0061` and `\141` are all equivalent regular expressions, where the last example shows octal syntax.

While supporting octal syntax isn't in and of itself a problem, it does make good error messages harder. That is, in PCRE based regex engines, syntax like `\0` invokes a backreference, which is explicitly unsupported in Rust's regex engine. However, many users expect it to be supported. Therefore, when octal support is disabled, the error message will explicitly mention that backreferences aren't supported.

Octal syntax is disabled by default.

#### `pub fn ignore_whitespace(&mut self, yes: bool) -> &mut ParserBuilder` [src]

Enable verbose mode in the regular expression.

When enabled, verbose mode permits insigificant whitespace in many places in the regular expression, as well as comments. Comments are started using `#` and continue until the end of the line.

By default, this is disabled. It may be selectively enabled in the regular expression by using the `x` flag regardless of this setting.

## Trait Implementations

### `impl Clone for ParserBuilder` [src]

#### `fn clone(&self) -> ParserBuilder` [src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`1.0.0 [src]

Performs copy-assignment from `source`. Read more

### `impl Default for ParserBuilder` [src]

#### `fn default() -> ParserBuilder` [src]

Returns the "default value" for a type. Read more

### `impl Debug for ParserBuilder` [src]

#### `fn fmt(&self, f: &mut Formatter) -> Result` [src]

Formats the value using the given formatter. Read more

## Auto Trait Implementations

### `impl Send for ParserBuilder`

### `impl Sync for ParserBuilder`

## Blanket Implementations

### `impl<T> From<T> for T` [src]

#### `fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `fn to_owned(&self) -> T` [src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `fn clone_into(&self, target: &mut T)` [src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into`)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `fn into(self) -> U` [src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

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