Import 'regex-syntax' package vesion 0.6.17
* Add OWNERS
Bug: 152884384
Test: make
Change-Id: I760a69ffc851039ceaff58980deece308a426aed
diff --git a/src/hir/print.rs b/src/hir/print.rs
new file mode 100644
index 0000000..eb44b93
--- /dev/null
+++ b/src/hir/print.rs
@@ -0,0 +1,368 @@
+/*!
+This module provides a regular expression printer for `Hir`.
+*/
+
+use std::fmt;
+
+use hir::visitor::{self, Visitor};
+use hir::{self, Hir, HirKind};
+use 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 { printer: self, wtr: wtr })
+ }
+}
+
+#[derive(Debug)]
+struct Writer<'p, W> {
+ printer: &'p mut Printer,
+ wtr: W,
+}
+
+impl<'p, W: fmt::Write> Visitor for Writer<'p, 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<'p, W: fmt::Write> Writer<'p, 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 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");
+ }
+}