fix OpAssert positive lookbehind

qingshi163 · qingshi163 · commit 39a648bce128 · 2021-02-03T13:32:48.000+02:00
diff --git a/src/engine.rs b/src/engine.rs
@@ -490,14 +490,24 @@ impl OpcodeDispatcher {
             SreOpcode::ASSERT => twice(
                 |drive| {
                     let back = drive.peek_code(2) as usize;
-                    let passed = drive.ctx().string_position - drive.state.start;
+                    let passed = drive.ctx().string_position;
                     if passed < back {
                         drive.ctx_mut().has_matched = Some(false);
                         return None;
                     }
+                    let back_offset = drive
+                        .state
+                        .string
+                        .back_offset(drive.ctx().string_offset, back);
+
                     drive.state.string_position = drive.ctx().string_position - back;
+
                     drive.push_new_context(3);
-                    drive.state.context_stack.last_mut().unwrap().toplevel = false;
+                    let child_ctx = drive.state.context_stack.last_mut().unwrap();
+                    child_ctx.toplevel = false;
+                    child_ctx.string_position -= back;
+                    child_ctx.string_offset = back_offset;
+
                     Some(())
                 },
                 |drive| {
@@ -512,14 +522,24 @@ impl OpcodeDispatcher {
             SreOpcode::ASSERT_NOT => twice(
                 |drive| {
                     let back = drive.peek_code(2) as usize;
-                    let passed = drive.ctx().string_position - drive.state.start;
+                    let passed = drive.ctx().string_position;
                     if passed < back {
                         drive.skip_code(drive.peek_code(1) as usize + 1);
                         return None;
                     }
+                    let back_offset = drive
+                        .state
+                        .string
+                        .back_offset(drive.ctx().string_offset, back);
+
                     drive.state.string_position = drive.ctx().string_position - back;
+
                     drive.push_new_context(3);
-                    drive.state.context_stack.last_mut().unwrap().toplevel = false;
+                    let child_ctx = drive.state.context_stack.last_mut().unwrap();
+                    child_ctx.toplevel = false;
+                    child_ctx.string_position -= back;
+                    child_ctx.string_offset = back_offset;
+
                     Some(())
                 },
                 |drive| {
diff --git a/tests/positive_lookbehind.py b/tests/positive_lookbehind.py
@@ -0,0 +1 @@
+re.compile(r'(?<=abc)def')
diff --git a/tests/positive_lookbehind.re b/tests/positive_lookbehind.re
@@ -0,0 +1,2 @@
+// '(?<=abc)def', flags=re.UNICODE
+Pattern { code: &[15, 4, 0, 3, 3, 4, 9, 3, 17, 97, 17, 98, 17, 99, 1, 17, 100, 17, 101, 17, 102, 1], flags: SreFlag::from_bits_truncate(32) }
diff --git a/tests/tests.rs b/tests/tests.rs
@@ -24,3 +24,12 @@ fn test_2427() {
     state = state.pymatch();
     assert!(state.has_matched == Some(true));
 }
+
+#[test]
+fn test_assert() {
+    // '(?<=abc)def', flags=re.UNICODE
+    let pattern = include!("positive_lookbehind.re");
+    let mut state = pattern.state("abcdef", 0..usize::MAX);
+    state = state.search();
+    assert!(state.has_matched == Some(true));
+}

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+// '(?<=abc)def', flags=re.UNICODE`
	`2`	`+Pattern { code: &[15, 4, 0, 3, 3, 4, 9, 3, 17, 97, 17, 98, 17, 99, 1, 17, 100, 17, 101, 17, 102, 1], flags: SreFlag::from_bits_truncate(32) }`