WIP structure

constants.rs

@@ -14,6 +14,10 @@
 use bitflags::bitflags;
 
 pub const SRE_MAGIC: usize = 20140917;
+pub const SRE_CODESIZE: usize = 4;
+pub const SRE_MAXREPEAT: usize = usize::max_value();
+pub const SRE_MAXGROUPS: usize = usize::max_value() / std::mem::size_of::<usize>() / 2;
+
 #[derive(num_enum::TryFromPrimitive, Debug)]
 #[repr(u32)]
 #[allow(non_camel_case_types)]

interp.rs

@@ -1,126 +1,409 @@
 // good luck to those that follow; here be dragons
 
+use super::constants::{SreFlag, SreOpcode, SRE_MAXREPEAT};
 use crate::builtins::PyStrRef;
-
-use super::constants::{SreFlag, SreOpcode};
-
+use rustpython_common::borrow::BorrowValue;
+use std::collections::HashMap;
 use std::convert::TryFrom;
-use std::{iter, slice};
 
-pub struct State {
+pub struct State<'a> {
+    // py_string: PyStrRef,
+    string: &'a str,
     start: usize,
-    s_pos: usize,
     end: usize,
-    pos: usize,
     flags: SreFlag,
+    pattern_codes: Vec<u32>,
     marks: Vec<usize>,
     lastindex: isize,
     marks_stack: Vec<usize>,
     context_stack: Vec<MatchContext>,
     repeat: Option<usize>,
-    s: PyStrRef,
+    string_position: usize,
 }
 
-// struct State1<'a> {
-//     state: &'a mut State,
-// }
-
-struct MatchContext {
-    s_pos: usize,
-    code_pos: usize,
-}
-
-// struct Context<'a> {
-//     context_stack: &mut Vec<MatchContext>,
-// }
-
-impl State {
-    pub fn new(s: PyStrRef, start: usize, end: usize, flags: SreFlag) -> Self {
-        let end = std::cmp::min(end, s.char_len());
+impl<'a> State<'a> {
+    pub(crate) fn new(
+        // py_string: PyStrRef,
+        string: &'a str,
+        start: usize,
+        end: usize,
+        flags: SreFlag,
+        pattern_codes: Vec<u32>,
+    ) -> Self {
+        // let string = py_string.borrow_value();
         Self {
+            // py_string,
+            string,
             start,
-            s_pos: start,
             end,
-            pos: start,
             flags,
-            marks: Vec::new(),
+            pattern_codes,
             lastindex: -1,
             marks_stack: Vec::new(),
             context_stack: Vec::new(),
             repeat: None,
-            s,
+            marks: Vec::new(),
+            string_position: start,
         }
     }
+
+    fn reset(&mut self) {
+        self.marks.clear();
+        self.lastindex = -1;
+        self.marks_stack.clear();
+        self.context_stack.clear();
+        self.repeat = None;
+    }
 }
 
-// struct OpcodeDispatcher {
-//     executing_contexts: HashMap<usize, Rc<State>>,
-// }
-
-pub struct BadSreCode;
-
-pub fn parse_ops(code: &[u32]) -> impl Iterator<Item = Result<Op, BadSreCode>> + '_ {
-    let mut it = code.iter().copied();
-    std::iter::from_fn(move || -> Option<Option<Op>> {
-        let op = it.next()?;
-        let op = SreOpcode::try_from(op)
-            .ok()
-            .and_then(|op| extract_code(op, &mut it));
-        Some(op)
-    })
-    .map(|x| x.ok_or(BadSreCode))
-}
-
-type It<'a> = iter::Copied<slice::Iter<'a, u32>>;
-fn extract_code(op: SreOpcode, it: &mut It) -> Option<Op> {
-    let skip = |it: &mut It| {
-        let skip = it.next()? as usize;
-        if skip > it.len() {
-            None
-        } else {
-            Some(skip)
-        }
+pub(crate) fn pymatch(mut state: State) -> bool {
+    let ctx = MatchContext {
+        string_position: state.start,
+        code_position: 0,
+        has_matched: None,
     };
-    match op {
-        SreOpcode::FAILURE => {}
-        SreOpcode::SUCCESS => {}
-        SreOpcode::ANY => {}
-        SreOpcode::ANY_ALL => {}
-        SreOpcode::ASSERT => {}
-        SreOpcode::ASSERT_NOT => {}
-        SreOpcode::AT => {}
-        SreOpcode::BRANCH => {}
-        SreOpcode::CALL => {}
-        SreOpcode::CATEGORY => {}
-        SreOpcode::CHARSET => {}
-        SreOpcode::BIGCHARSET => {}
-        SreOpcode::GROUPREF => {}
-        SreOpcode::GROUPREF_EXISTS => {}
-        SreOpcode::GROUPREF_IGNORE => {}
-        SreOpcode::IN => {}
-        SreOpcode::IN_IGNORE => {}
-        SreOpcode::INFO => {
-            // let skip = it.next()?;
+    state.context_stack.push(ctx);
+
+    let mut has_matched = None;
+    loop {
+        if state.context_stack.is_empty() {
+            break;
+        }
+        let ctx_id = state.context_stack.len() - 1;
+        let mut drive = MatchContextDrive::drive(ctx_id, state);
+        let mut dispatcher = OpcodeDispatcher::new();
+
+        has_matched = dispatcher.pymatch(&mut drive);
+        state = drive.take();
+        if has_matched.is_some() {
+            state.context_stack.pop();
         }
-        SreOpcode::JUMP => {}
-        SreOpcode::LITERAL => {}
-        SreOpcode::LITERAL_IGNORE => {}
-        SreOpcode::MARK => {}
-        SreOpcode::MAX_UNTIL => {}
-        SreOpcode::MIN_UNTIL => {}
-        SreOpcode::NOT_LITERAL => {}
-        SreOpcode::NOT_LITERAL_IGNORE => {}
-        SreOpcode::NEGATE => {}
-        SreOpcode::RANGE => {}
-        SreOpcode::REPEAT => {}
-        SreOpcode::REPEAT_ONE => {}
-        SreOpcode::SUBPATTERN => {}
-        SreOpcode::MIN_REPEAT_ONE => {}
-        SreOpcode::RANGE_IGNORE => {}
     }
-    todo!()
+    has_matched.unwrap_or(false)
 }
 
-pub enum Op {
-    Info {},
+#[derive(Debug, Copy, Clone)]
+struct MatchContext {
+    string_position: usize,
+    code_position: usize,
+    has_matched: Option<bool>,
+}
+
+struct MatchContextDrive<'a> {
+    state: State<'a>,
+    ctx_id: usize,
+}
+
+impl<'a> MatchContextDrive<'a> {
+    fn id(&self) -> usize {
+        self.ctx_id
+    }
+    fn ctx_mut(&mut self) -> &mut MatchContext {
+        &mut self.state.context_stack[self.ctx_id]
+    }
+    fn ctx(&self) -> &MatchContext {
+        &self.state.context_stack[self.ctx_id]
+    }
+    fn push_new_context(&mut self, pattern_offset: usize) -> usize {
+        let ctx = self.ctx();
+        let child_ctx = MatchContext {
+            string_position: ctx.string_position,
+            code_position: ctx.code_position + pattern_offset,
+            has_matched: None,
+        };
+        self.state.context_stack.push(child_ctx);
+        self.state.context_stack.len() - 1
+    }
+    fn drive(ctx_id: usize, state: State<'a>) -> Self {
+        Self { state, ctx_id }
+    }
+    fn take(self) -> State<'a> {
+        self.state
+    }
+    fn str(&self) -> &str {
+        unsafe {
+            std::str::from_utf8_unchecked(
+                &self.state.string.as_bytes()[self.ctx().string_position..],
+            )
+        }
+    }
+    fn peek_char(&self) -> char {
+        self.str().chars().next().unwrap()
+    }
+    fn peek_code(&self, peek: usize) -> u32 {
+        self.state.pattern_codes[self.ctx().code_position + peek]
+    }
+    fn skip_char(&mut self, skip_count: usize) {
+        let skipped = self.str().char_indices().nth(skip_count).unwrap().0;
+        self.ctx_mut().string_position += skipped;
+    }
+    fn skip_code(&mut self, skip_count: usize) {
+        self.ctx_mut().code_position += skip_count;
+    }
+    fn remaining_chars(&self) -> usize {
+        let end = self.state.end;
+        end - self.ctx().string_position + self.str().len()
+    }
+    fn remaining_codes(&self) -> usize {
+        self.state.pattern_codes.len() - self.ctx().code_position
+    }
+    fn at_beginning(&self) -> bool {
+        self.ctx().string_position == 0
+    }
+    fn at_end(&self) -> bool {
+        self.str().is_empty()
+    }
+    fn at_linebreak(&self) -> bool {
+        match self.str().chars().next() {
+            Some(c) => c == '\n',
+            None => false,
+        }
+    }
+}
+
+struct OpcodeDispatcher {
+    executing_contexts: HashMap<usize, Box<dyn OpcodeExecutor>>,
+}
+
+macro_rules! once {
+    ($val:expr) => {
+        Box::new(OpEmpty {})
+    };
+}
+
+trait OpcodeExecutor {
+    fn next(&mut self, drive: &mut MatchContextDrive) -> Option<()>;
+}
+
+struct OpFailure {}
+impl OpcodeExecutor for OpFailure {
+    fn next(&mut self, drive: &mut MatchContextDrive) -> Option<()> {
+        drive.ctx_mut().has_matched = Some(false);
+        None
+    }
+}
+
+struct OpEmpty {}
+impl OpcodeExecutor for OpEmpty {
+    fn next(&mut self, drive: &mut MatchContextDrive) -> Option<()> {
+        None
+    }
+}
+
+struct OpOnce<F> {
+    f: Option<F>,
+}
+impl<F: FnOnce(&mut MatchContextDrive)> OpcodeExecutor for OpOnce<F> {
+    fn next(&mut self, drive: &mut MatchContextDrive) -> Option<()> {
+        let f = self.f.take()?;
+        f(drive);
+        None
+    }
+}
+fn once<F: FnOnce(&mut MatchContextDrive)>(f: F) -> Box<OpOnce<F>> {
+    Box::new(OpOnce { f: Some(f) })
+}
+
+struct OpMinRepeatOne {
+    trace_id: usize,
+    mincount: usize,
+    maxcount: usize,
+    count: usize,
+    child_ctx_id: usize,
+}
+impl OpcodeExecutor for OpMinRepeatOne {
+    fn next(&mut self, drive: &mut MatchContextDrive) -> Option<()> {
+        match self.trace_id {
+            0 => self._0(drive),
+            _ => unreachable!(),
+        }
+    }
+}
+impl Default for OpMinRepeatOne {
+    fn default() -> Self {
+        OpMinRepeatOne {
+            trace_id: 0,
+            mincount: 0,
+            maxcount: 0,
+            count: 0,
+            child_ctx_id: 0,
+        }
+    }
+}
+impl OpMinRepeatOne {
+    fn _0(&mut self, drive: &mut MatchContextDrive) -> Option<()> {
+        self.mincount = drive.peek_code(2) as usize;
+        self.maxcount = drive.peek_code(3) as usize;
+
+        if drive.remaining_chars() < self.mincount {
+            drive.ctx_mut().has_matched = Some(false);
+            return None;
+        }
+
+        drive.state.string_position = drive.ctx().string_position;
+
+        self.count = if self.mincount == 0 {
+            0
+        } else {
+            let count = count_repetitions(drive, self.mincount);
+            if count < self.mincount {
+                drive.ctx_mut().has_matched = Some(false);
+                return None;
+            }
+            drive.skip_char(count);
+            count
+        };
+
+        if drive.peek_code(drive.peek_code(1) as usize + 1) == SreOpcode::SUCCESS as u32 {
+            drive.state.string_position = drive.ctx().string_position;
+            drive.ctx_mut().has_matched = Some(true);
+            return None;
+        }
+
+        // mark push
+        self.trace_id = 1;
+        self._1(drive)
+    }
+    fn _1(&mut self, drive: &mut MatchContextDrive) -> Option<()> {
+        if self.maxcount == SRE_MAXREPEAT || self.count <= self.maxcount {
+            drive.state.string_position = drive.ctx().string_position;
+            self.child_ctx_id = drive.push_new_context(drive.peek_code(1) as usize + 1);
+            self.trace_id = 2;
+            return Some(());
+        }
+
+        // mark discard
+        drive.ctx_mut().has_matched = Some(false);
+        None
+    }
+    fn _2(&mut self, drive: &mut MatchContextDrive) -> Option<()> {
+        if let Some(true) = drive.state.context_stack[self.child_ctx_id].has_matched {
+            drive.ctx_mut().has_matched = Some(true);
+            return None;
+        }
+        drive.state.string_position = drive.ctx().string_position;
+        if count_repetitions(drive, 1) == 0 {
+            self.trace_id = 3;
+            return self._3(drive);
+        }
+        drive.skip_char(1);
+        self.count += 1;
+        // marks pop keep
+        self.trace_id = 1;
+        self._1(drive)
+    }
+    fn _3(&mut self, drive: &mut MatchContextDrive) -> Option<()> {
+        // mark discard
+        drive.ctx_mut().has_matched = Some(false);
+        None
+    }
+}
+
+impl OpcodeDispatcher {
+    fn new() -> Self {
+        Self {
+            executing_contexts: HashMap::new(),
+        }
+    }
+    // Returns True if the current context matches, False if it doesn't and
+    // None if matching is not finished, ie must be resumed after child
+    // contexts have been matched.
+    fn pymatch(&mut self, drive: &mut MatchContextDrive) -> Option<bool> {
+        while drive.remaining_codes() > 0 && drive.ctx().has_matched.is_none() {
+            let code = drive.peek_code(0);
+            let opcode = SreOpcode::try_from(code).unwrap();
+            self.dispatch(opcode, drive);
+            // self.drive = self.drive;
+        }
+        match drive.ctx().has_matched {
+            Some(matched) => Some(matched),
+            None => {
+                drive.ctx_mut().has_matched = Some(false);
+                Some(false)
+            }
+        }
+    }
+
+    // Dispatches a context on a given opcode. Returns True if the context
+    // is done matching, False if it must be resumed when next encountered.
+    fn dispatch(&mut self, opcode: SreOpcode, drive: &mut MatchContextDrive) -> bool {
+        let mut executor = match self.executing_contexts.remove_entry(&drive.id()) {
+            Some((_, mut executor)) => executor,
+            None => self.dispatch_table(opcode, drive),
+        };
+        if let Some(()) = executor.next(drive) {
+            self.executing_contexts.insert(drive.id(), executor);
+            false
+        } else {
+            true
+        }
+    }
+
+    fn dispatch_table(
+        &mut self,
+        opcode: SreOpcode,
+        drive: &mut MatchContextDrive,
+    ) -> Box<dyn OpcodeExecutor> {
+        // move || {
+        match opcode {
+            SreOpcode::FAILURE => {
+                Box::new(OpFailure {})
+            }
+            SreOpcode::SUCCESS => once(|drive| {
+                drive.state.string_position = drive.ctx().string_position;
+                drive.ctx_mut().has_matched = Some(true);
+            }),
+            SreOpcode::ANY => once!(true),
+            SreOpcode::ANY_ALL => once!(true),
+            SreOpcode::ASSERT => once!(true),
+            SreOpcode::ASSERT_NOT => once!(true),
+            SreOpcode::AT => once!(true),
+            SreOpcode::BRANCH => once!(true),
+            SreOpcode::CALL => once!(true),
+            SreOpcode::CATEGORY => once!(true),
+            SreOpcode::CHARSET => once!(true),
+            SreOpcode::BIGCHARSET => once!(true),
+            SreOpcode::GROUPREF => once!(true),
+            SreOpcode::GROUPREF_EXISTS => once!(true),
+            SreOpcode::GROUPREF_IGNORE => once!(true),
+            SreOpcode::IN => once!(true),
+            SreOpcode::IN_IGNORE => once!(true),
+            SreOpcode::INFO => once!(true),
+            SreOpcode::JUMP => once!(true),
+            SreOpcode::LITERAL => {
+                if drive.at_end() || drive.peek_char() as u32 != drive.peek_code(1) {
+                    drive.ctx_mut().has_matched = Some(false);
+                } else {
+                    drive.skip_char(1);
+                }
+                drive.skip_code(2);
+                once!(true)
+            }
+            SreOpcode::LITERAL_IGNORE => once!(true),
+            SreOpcode::MARK => once!(true),
+            SreOpcode::MAX_UNTIL => once!(true),
+            SreOpcode::MIN_UNTIL => once!(true),
+            SreOpcode::NOT_LITERAL => once!(true),
+            SreOpcode::NOT_LITERAL_IGNORE => once!(true),
+            SreOpcode::NEGATE => once!(true),
+            SreOpcode::RANGE => once!(true),
+            SreOpcode::REPEAT => once!(true),
+            SreOpcode::REPEAT_ONE => once!(true),
+            SreOpcode::SUBPATTERN => once!(true),
+            SreOpcode::MIN_REPEAT_ONE => Box::new(OpMinRepeatOne::default()),
+            SreOpcode::RANGE_IGNORE => once!(true),
+        }
+    }
+}
+
+// Returns the number of repetitions of a single item, starting from the
+// current string position. The code pointer is expected to point to a
+// REPEAT_ONE operation (with the repeated 4 ahead).
+fn count_repetitions(drive: &mut MatchContextDrive, maxcount: usize) -> usize {
+    let mut count = 0;
+    let mut real_maxcount = drive.state.end - drive.ctx().string_position;
+    if maxcount < real_maxcount && maxcount != SRE_MAXREPEAT {
+        real_maxcount = maxcount;
+    }
+    count
 }