368 lines
11 KiB
Rust
368 lines
11 KiB
Rust
/*!
|
|
This module provides a regular expression printer for `Hir`.
|
|
*/
|
|
|
|
use std::fmt;
|
|
|
|
use crate::hir::visitor::{self, Visitor};
|
|
use crate::hir::{self, Hir, HirKind};
|
|
use crate::is_meta_character;
|
|
|
|
/// A builder for constructing a printer.
|
|
///
|
|
/// Note that since a printer doesn't have any configuration knobs, this type
|
|
/// remains unexported.
|
|
#[derive(Clone, Debug)]
|
|
struct PrinterBuilder {
|
|
_priv: (),
|
|
}
|
|
|
|
impl Default for PrinterBuilder {
|
|
fn default() -> PrinterBuilder {
|
|
PrinterBuilder::new()
|
|
}
|
|
}
|
|
|
|
impl PrinterBuilder {
|
|
fn new() -> PrinterBuilder {
|
|
PrinterBuilder { _priv: () }
|
|
}
|
|
|
|
fn build(&self) -> Printer {
|
|
Printer { _priv: () }
|
|
}
|
|
}
|
|
|
|
/// A printer for a regular expression's high-level intermediate
|
|
/// representation.
|
|
///
|
|
/// A printer converts a high-level intermediate representation (HIR) to a
|
|
/// regular expression pattern string. This particular printer uses constant
|
|
/// stack space and heap space proportional to the size of the HIR.
|
|
///
|
|
/// Since this printer is only using the HIR, the pattern it prints will likely
|
|
/// not resemble the original pattern at all. For example, a pattern like
|
|
/// `\pL` will have its entire class written out.
|
|
///
|
|
/// The purpose of this printer is to provide a means to mutate an HIR and then
|
|
/// build a regular expression from the result of that mutation. (A regex
|
|
/// library could provide a constructor from this HIR explicitly, but that
|
|
/// creates an unnecessary public coupling between the regex library and this
|
|
/// specific HIR representation.)
|
|
#[derive(Debug)]
|
|
pub struct Printer {
|
|
_priv: (),
|
|
}
|
|
|
|
impl Printer {
|
|
/// Create a new printer.
|
|
pub fn new() -> Printer {
|
|
PrinterBuilder::new().build()
|
|
}
|
|
|
|
/// Print the given `Ast` to the given writer. The writer must implement
|
|
/// `fmt::Write`. Typical implementations of `fmt::Write` that can be used
|
|
/// here are a `fmt::Formatter` (which is available in `fmt::Display`
|
|
/// implementations) or a `&mut String`.
|
|
pub fn print<W: fmt::Write>(&mut self, hir: &Hir, wtr: W) -> fmt::Result {
|
|
visitor::visit(hir, Writer { wtr })
|
|
}
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
struct Writer<W> {
|
|
wtr: W,
|
|
}
|
|
|
|
impl<W: fmt::Write> Visitor for Writer<W> {
|
|
type Output = ();
|
|
type Err = fmt::Error;
|
|
|
|
fn finish(self) -> fmt::Result {
|
|
Ok(())
|
|
}
|
|
|
|
fn visit_pre(&mut self, hir: &Hir) -> fmt::Result {
|
|
match *hir.kind() {
|
|
HirKind::Empty
|
|
| HirKind::Repetition(_)
|
|
| HirKind::Concat(_)
|
|
| HirKind::Alternation(_) => {}
|
|
HirKind::Literal(hir::Literal::Unicode(c)) => {
|
|
self.write_literal_char(c)?;
|
|
}
|
|
HirKind::Literal(hir::Literal::Byte(b)) => {
|
|
self.write_literal_byte(b)?;
|
|
}
|
|
HirKind::Class(hir::Class::Unicode(ref cls)) => {
|
|
self.wtr.write_str("[")?;
|
|
for range in cls.iter() {
|
|
if range.start() == range.end() {
|
|
self.write_literal_char(range.start())?;
|
|
} else {
|
|
self.write_literal_char(range.start())?;
|
|
self.wtr.write_str("-")?;
|
|
self.write_literal_char(range.end())?;
|
|
}
|
|
}
|
|
self.wtr.write_str("]")?;
|
|
}
|
|
HirKind::Class(hir::Class::Bytes(ref cls)) => {
|
|
self.wtr.write_str("(?-u:[")?;
|
|
for range in cls.iter() {
|
|
if range.start() == range.end() {
|
|
self.write_literal_class_byte(range.start())?;
|
|
} else {
|
|
self.write_literal_class_byte(range.start())?;
|
|
self.wtr.write_str("-")?;
|
|
self.write_literal_class_byte(range.end())?;
|
|
}
|
|
}
|
|
self.wtr.write_str("])")?;
|
|
}
|
|
HirKind::Anchor(hir::Anchor::StartLine) => {
|
|
self.wtr.write_str("(?m:^)")?;
|
|
}
|
|
HirKind::Anchor(hir::Anchor::EndLine) => {
|
|
self.wtr.write_str("(?m:$)")?;
|
|
}
|
|
HirKind::Anchor(hir::Anchor::StartText) => {
|
|
self.wtr.write_str(r"\A")?;
|
|
}
|
|
HirKind::Anchor(hir::Anchor::EndText) => {
|
|
self.wtr.write_str(r"\z")?;
|
|
}
|
|
HirKind::WordBoundary(hir::WordBoundary::Unicode) => {
|
|
self.wtr.write_str(r"\b")?;
|
|
}
|
|
HirKind::WordBoundary(hir::WordBoundary::UnicodeNegate) => {
|
|
self.wtr.write_str(r"\B")?;
|
|
}
|
|
HirKind::WordBoundary(hir::WordBoundary::Ascii) => {
|
|
self.wtr.write_str(r"(?-u:\b)")?;
|
|
}
|
|
HirKind::WordBoundary(hir::WordBoundary::AsciiNegate) => {
|
|
self.wtr.write_str(r"(?-u:\B)")?;
|
|
}
|
|
HirKind::Group(ref x) => match x.kind {
|
|
hir::GroupKind::CaptureIndex(_) => {
|
|
self.wtr.write_str("(")?;
|
|
}
|
|
hir::GroupKind::CaptureName { ref name, .. } => {
|
|
write!(self.wtr, "(?P<{}>", name)?;
|
|
}
|
|
hir::GroupKind::NonCapturing => {
|
|
self.wtr.write_str("(?:")?;
|
|
}
|
|
},
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
fn visit_post(&mut self, hir: &Hir) -> fmt::Result {
|
|
match *hir.kind() {
|
|
// Handled during visit_pre
|
|
HirKind::Empty
|
|
| HirKind::Literal(_)
|
|
| HirKind::Class(_)
|
|
| HirKind::Anchor(_)
|
|
| HirKind::WordBoundary(_)
|
|
| HirKind::Concat(_)
|
|
| HirKind::Alternation(_) => {}
|
|
HirKind::Repetition(ref x) => {
|
|
match x.kind {
|
|
hir::RepetitionKind::ZeroOrOne => {
|
|
self.wtr.write_str("?")?;
|
|
}
|
|
hir::RepetitionKind::ZeroOrMore => {
|
|
self.wtr.write_str("*")?;
|
|
}
|
|
hir::RepetitionKind::OneOrMore => {
|
|
self.wtr.write_str("+")?;
|
|
}
|
|
hir::RepetitionKind::Range(ref x) => match *x {
|
|
hir::RepetitionRange::Exactly(m) => {
|
|
write!(self.wtr, "{{{}}}", m)?;
|
|
}
|
|
hir::RepetitionRange::AtLeast(m) => {
|
|
write!(self.wtr, "{{{},}}", m)?;
|
|
}
|
|
hir::RepetitionRange::Bounded(m, n) => {
|
|
write!(self.wtr, "{{{},{}}}", m, n)?;
|
|
}
|
|
},
|
|
}
|
|
if !x.greedy {
|
|
self.wtr.write_str("?")?;
|
|
}
|
|
}
|
|
HirKind::Group(_) => {
|
|
self.wtr.write_str(")")?;
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
fn visit_alternation_in(&mut self) -> fmt::Result {
|
|
self.wtr.write_str("|")
|
|
}
|
|
}
|
|
|
|
impl<W: fmt::Write> Writer<W> {
|
|
fn write_literal_char(&mut self, c: char) -> fmt::Result {
|
|
if is_meta_character(c) {
|
|
self.wtr.write_str("\\")?;
|
|
}
|
|
self.wtr.write_char(c)
|
|
}
|
|
|
|
fn write_literal_byte(&mut self, b: u8) -> fmt::Result {
|
|
let c = b as char;
|
|
if c <= 0x7F as char && !c.is_control() && !c.is_whitespace() {
|
|
self.write_literal_char(c)
|
|
} else {
|
|
write!(self.wtr, "(?-u:\\x{:02X})", b)
|
|
}
|
|
}
|
|
|
|
fn write_literal_class_byte(&mut self, b: u8) -> fmt::Result {
|
|
let c = b as char;
|
|
if c <= 0x7F as char && !c.is_control() && !c.is_whitespace() {
|
|
self.write_literal_char(c)
|
|
} else {
|
|
write!(self.wtr, "\\x{:02X}", b)
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::Printer;
|
|
use crate::ParserBuilder;
|
|
|
|
fn roundtrip(given: &str, expected: &str) {
|
|
roundtrip_with(|b| b, given, expected);
|
|
}
|
|
|
|
fn roundtrip_bytes(given: &str, expected: &str) {
|
|
roundtrip_with(|b| b.allow_invalid_utf8(true), given, expected);
|
|
}
|
|
|
|
fn roundtrip_with<F>(mut f: F, given: &str, expected: &str)
|
|
where
|
|
F: FnMut(&mut ParserBuilder) -> &mut ParserBuilder,
|
|
{
|
|
let mut builder = ParserBuilder::new();
|
|
f(&mut builder);
|
|
let hir = builder.build().parse(given).unwrap();
|
|
|
|
let mut printer = Printer::new();
|
|
let mut dst = String::new();
|
|
printer.print(&hir, &mut dst).unwrap();
|
|
|
|
// Check that the result is actually valid.
|
|
builder.build().parse(&dst).unwrap();
|
|
|
|
assert_eq!(expected, dst);
|
|
}
|
|
|
|
#[test]
|
|
fn print_literal() {
|
|
roundtrip("a", "a");
|
|
roundtrip(r"\xff", "\u{FF}");
|
|
roundtrip_bytes(r"\xff", "\u{FF}");
|
|
roundtrip_bytes(r"(?-u)\xff", r"(?-u:\xFF)");
|
|
roundtrip("☃", "☃");
|
|
}
|
|
|
|
#[test]
|
|
fn print_class() {
|
|
roundtrip(r"[a]", r"[a]");
|
|
roundtrip(r"[a-z]", r"[a-z]");
|
|
roundtrip(r"[a-z--b-c--x-y]", r"[ad-wz]");
|
|
roundtrip(r"[^\x01-\u{10FFFF}]", "[\u{0}]");
|
|
roundtrip(r"[-]", r"[\-]");
|
|
roundtrip(r"[☃-⛄]", r"[☃-⛄]");
|
|
|
|
roundtrip(r"(?-u)[a]", r"(?-u:[a])");
|
|
roundtrip(r"(?-u)[a-z]", r"(?-u:[a-z])");
|
|
roundtrip_bytes(r"(?-u)[a-\xFF]", r"(?-u:[a-\xFF])");
|
|
|
|
// The following test that the printer escapes meta characters
|
|
// in character classes.
|
|
roundtrip(r"[\[]", r"[\[]");
|
|
roundtrip(r"[Z-_]", r"[Z-_]");
|
|
roundtrip(r"[Z-_--Z]", r"[\[-_]");
|
|
|
|
// The following test that the printer escapes meta characters
|
|
// in byte oriented character classes.
|
|
roundtrip_bytes(r"(?-u)[\[]", r"(?-u:[\[])");
|
|
roundtrip_bytes(r"(?-u)[Z-_]", r"(?-u:[Z-_])");
|
|
roundtrip_bytes(r"(?-u)[Z-_--Z]", r"(?-u:[\[-_])");
|
|
}
|
|
|
|
#[test]
|
|
fn print_anchor() {
|
|
roundtrip(r"^", r"\A");
|
|
roundtrip(r"$", r"\z");
|
|
roundtrip(r"(?m)^", r"(?m:^)");
|
|
roundtrip(r"(?m)$", r"(?m:$)");
|
|
}
|
|
|
|
#[test]
|
|
fn print_word_boundary() {
|
|
roundtrip(r"\b", r"\b");
|
|
roundtrip(r"\B", r"\B");
|
|
roundtrip(r"(?-u)\b", r"(?-u:\b)");
|
|
roundtrip_bytes(r"(?-u)\B", r"(?-u:\B)");
|
|
}
|
|
|
|
#[test]
|
|
fn print_repetition() {
|
|
roundtrip("a?", "a?");
|
|
roundtrip("a??", "a??");
|
|
roundtrip("(?U)a?", "a??");
|
|
|
|
roundtrip("a*", "a*");
|
|
roundtrip("a*?", "a*?");
|
|
roundtrip("(?U)a*", "a*?");
|
|
|
|
roundtrip("a+", "a+");
|
|
roundtrip("a+?", "a+?");
|
|
roundtrip("(?U)a+", "a+?");
|
|
|
|
roundtrip("a{1}", "a{1}");
|
|
roundtrip("a{1,}", "a{1,}");
|
|
roundtrip("a{1,5}", "a{1,5}");
|
|
roundtrip("a{1}?", "a{1}?");
|
|
roundtrip("a{1,}?", "a{1,}?");
|
|
roundtrip("a{1,5}?", "a{1,5}?");
|
|
roundtrip("(?U)a{1}", "a{1}?");
|
|
roundtrip("(?U)a{1,}", "a{1,}?");
|
|
roundtrip("(?U)a{1,5}", "a{1,5}?");
|
|
}
|
|
|
|
#[test]
|
|
fn print_group() {
|
|
roundtrip("()", "()");
|
|
roundtrip("(?P<foo>)", "(?P<foo>)");
|
|
roundtrip("(?:)", "(?:)");
|
|
|
|
roundtrip("(a)", "(a)");
|
|
roundtrip("(?P<foo>a)", "(?P<foo>a)");
|
|
roundtrip("(?:a)", "(?:a)");
|
|
|
|
roundtrip("((((a))))", "((((a))))");
|
|
}
|
|
|
|
#[test]
|
|
fn print_alternation() {
|
|
roundtrip("|", "|");
|
|
roundtrip("||", "||");
|
|
|
|
roundtrip("a|b", "a|b");
|
|
roundtrip("a|b|c", "a|b|c");
|
|
roundtrip("foo|bar|quux", "foo|bar|quux");
|
|
}
|
|
}
|