Enum FinalNode

Source

pub enum FinalNode {
    Byte(u8),
    AnyByte,
    Seq(Vec<FinalNode>),
    Class(bool, Vec<ClassItem>),
    Group(Box<FinalNode>),
    NonCapturingGroup(Box<FinalNode>),
    Alt(Vec<FinalNode>),
    Repeat(Box<FinalNode>, usize, Option<usize>),
}

Expand description

A completely parsed element of a regular expression abstract syntax tree (AST).

A FinalNode could represent an entire regular expression (it is the root) or a small part of one.

Since a regular expression ultimately processes bytes, the leaves of the AST are nodes with bytes:

Byte
AnyByte

All other variants are edges of the AST:

Seq
Class
Group
Alt
Repeat

Variants§

§

Byte(u8)

Byte(u8)

A byte of input. This may be a non-printable byte that was escaped in the source regular expression.

§Examples

use safe_regex_compiler::parser::parse;
use safe_regex_compiler::parser::FinalNode;
assert_eq!(
    Ok(FinalNode::Byte(b'a')),
    parse(br"a"),
);
assert_eq!(
    Ok(FinalNode::Byte(b'\n')),
    parse(br"\n"),
);
assert_eq!(
    Ok(FinalNode::Byte(b'\\')),
    parse(br"\\"),
);
assert_eq!(
    Ok(FinalNode::Byte(0x12)),
    parse(br"\x12"),
);

§

AnyByte

AnyByte

Matches any byte of input. This is the . operator.

§Example

use safe_regex_compiler::parser::parse;
use safe_regex_compiler::parser::FinalNode;
assert_eq!(
    Ok(FinalNode::AnyByte),
    parse(br"."),
);

§

Seq(Vec<FinalNode>)

Seq(Vec<FinalNode>)

A sequence of nodes.

§Example

use safe_regex_compiler::parser::parse;
use safe_regex_compiler::parser::FinalNode;
assert_eq!(
    Ok(FinalNode::Seq(vec![
        FinalNode::Byte(b'a'),
        FinalNode::Byte(b'b')],
    )),
    parse(br"ab"),
);

§

Class(bool, Vec<ClassItem>)

Class(inclusive: bool, Vec<ClassItem>)

A character class. Matches any byte in the class.

See ClassItem

§Examples

use safe_regex_compiler::parser::parse;
use safe_regex_compiler::parser::FinalNode;
use safe_regex_compiler::parser::ClassItem;
assert_eq!(
    Ok(FinalNode::Class(true, vec![
        ClassItem::Byte(b'a'),
        ClassItem::Byte(b'b'),
    ])),
    parse(br"[ab]"),
);
assert_eq!(
    Ok(FinalNode::Class(false, vec![
        ClassItem::Byte(b'a'),
        ClassItem::Byte(b'b'),
    ])),
    parse(br"[^ab]"),
);
assert_eq!(
    Ok(FinalNode::Class(true, vec![
        ClassItem::ByteRange(b'0', b'9'),
    ])),
    parse(br"[0-9]"),
);

§

Group(Box<FinalNode>)

Group(Box<FinalNode>)

A capturing group of nodes. Regular expression authors use it to override operator precedence rules and to capture sub-slices of input.

§Examples

use safe_regex_compiler::parser::parse;
use safe_regex_compiler::parser::FinalNode;
assert_eq!(
   Ok(FinalNode::Seq(vec![
      FinalNode::Byte(b'a'),
      FinalNode::Group(Box::new(
         FinalNode::Alt(vec![
            FinalNode::Byte(b'b'),
            FinalNode::Byte(b'c'),
         ])
      )),
   ])),
   parse(br"a(b|c)"),
);
assert_eq!(
   Ok(FinalNode::Repeat(
      Box::new(FinalNode::Group(Box::new(
          FinalNode::Seq(vec![
             FinalNode::Byte(b'a'),
             FinalNode::Byte(b'b'),
          ])
      ))),
      0,    // min
      None, // max
   )),
   parse(br"(ab)*"),
);

§

NonCapturingGroup(Box<FinalNode>)

NonCapturingGroup(Box<FinalNode>)

A non-capturing group of nodes. Regular expression authors use it to override operator precedence rules.

§Examples

use safe_regex_compiler::parser::parse;
use safe_regex_compiler::parser::FinalNode;
assert_eq!(
   Ok(FinalNode::Seq(vec![
      FinalNode::Byte(b'a'),
      FinalNode::NonCapturingGroup(Box::new(
         FinalNode::Alt(vec![
            FinalNode::Byte(b'b'),
            FinalNode::Byte(b'c'),
         ])
      )),
   ])),
   parse(br"a(?:b|c)"),
);
assert_eq!(
   Ok(FinalNode::Repeat(
      Box::new(FinalNode::NonCapturingGroup(Box::new(
          FinalNode::Seq(vec![
             FinalNode::Byte(b'a'),
             FinalNode::Byte(b'b'),
          ])
      ))),
      0,    // min
      None, // max
   )),
   parse(br"(?:ab)*"),
);

§

Alt(Vec<FinalNode>)

Alt(Vec<FinalNode>)

A list of alternate nodes. The input can match any of them.

§Examples

use safe_regex_compiler::parser::parse;
use safe_regex_compiler::parser::FinalNode;
assert_eq!(
    Ok(FinalNode::Alt(vec![
        FinalNode::Byte(b'a'),
        FinalNode::Byte(b'b'),
    ])),
    parse(br"a|b"),
);
assert_eq!(
    Ok(FinalNode::Alt(vec![
        FinalNode::Byte(b'a'),
        FinalNode::Byte(b'b'),
        FinalNode::Seq(vec![
            FinalNode::AnyByte,
            FinalNode::Byte(b'c'),
        ]),
    ])),
    parse(br"a|b|.c"),
);

§

Repeat(Box<FinalNode>, usize, Option<usize>)

Repeat(Box<FinalNode>, min: usize, max: Option<usize>)

A repetition of a node. It contains the minimum number of repetitions and an optional inclusive maximum number.

§Examples

use safe_regex_compiler::parser::parse;
use safe_regex_compiler::parser::FinalNode;
assert_eq!(
    Ok(FinalNode::Repeat(
        Box::new(FinalNode::Byte(b'a')),
        0,       // min
        Some(1), // max
    )),
    parse(br"a?"),
);
assert_eq!(
    Ok(FinalNode::Repeat(
        Box::new(FinalNode::Byte(b'a')),
        0,    // min
        None, // max
    )),
    parse(br"a*"),
);
assert_eq!(
    Ok(FinalNode::Repeat(
        Box::new(FinalNode::Byte(b'a')),
        1,    // min
        None, // max
    )),
    parse(br"a+"),
);
assert_eq!(
    Ok(FinalNode::Repeat(
        Box::new(FinalNode::Byte(b'a')),
        5,       // min
        Some(5), // max
    )),
    parse(br"a{5}"),
);
assert_eq!(
    Ok(FinalNode::Repeat(
        Box::new(FinalNode::Byte(b'a')),
        5,    // min
        None, // max
    )),
    parse(br"a{5,}"),
);
assert_eq!(
    Ok(FinalNode::Repeat(
        Box::new(FinalNode::Byte(b'a')),
        0,       // min
        Some(7), // max
    )),
    parse(br"a{,7}"),
);
assert_eq!(
    Ok(FinalNode::Repeat(
        Box::new(FinalNode::Byte(b'a')),
        5,       // min
        Some(7), // max
    )),
    parse(br"a{5,7}"),
);
assert_eq!(
    Ok(FinalNode::Repeat(
        Box::new(FinalNode::Byte(b'a')),
        0,    // min
        None, // max
    )),
    parse(br"a{,}"),
);