feat(common): add support for start parameter in StringFind

ibis/backends/base/sql/alchemy/registry.py

@@ -441,13 +441,19 @@ def _substring(t, op):
 
 def _gen_string_find(func):
     def string_find(t, op):
-        if op.start is not None:
-            raise NotImplementedError("`start` not yet implemented")
-
         if op.end is not None:
             raise NotImplementedError("`end` not yet implemented")
 
-        return func(t.translate(op.arg), t.translate(op.substr)) - 1
+        arg = t.translate(op.arg)
+        sub_string = t.translate(op.substr)
+
+        if (op_start := op.start) is not None:
+            start = t.translate(op_start)
+            arg = sa.func.substr(arg, start + 1)
+            pos = func(arg, sub_string)
+            return sa.case((pos > 0, pos - 1 + start), else_=-1)
+
+        return func(arg, sub_string) - 1
 
     return string_find
 

ibis/backends/clickhouse/compiler/values.py

@@ -281,15 +281,16 @@ def _substring(op, **kw):
 
 @translate_val.register(ops.StringFind)
 def _string_find(op, **kw):
-    if op.start is not None:
-        raise com.UnsupportedOperationError(
-            "String find doesn't support start argument"
-        )
     if op.end is not None:
         raise com.UnsupportedOperationError("String find doesn't support end argument")
 
     arg = translate_val(op.arg, **kw)
     substr = translate_val(op.substr, **kw)
+
+    if op.start is not None:
+        op_start = translate_val(op.start)
+        return f"locate({arg}, {substr}, {op_start}) - 1"
+
     return f"locate({arg}, {substr}) - 1"
 
 

ibis/backends/datafusion/compiler.py

@@ -530,13 +530,19 @@ def regex_replace(op):
 
 @translate.register(ops.StringFind)
 def string_find(op):
+    if op.end is not None:
+        raise NotImplementedError("`end` not yet implemented")
+
     arg = translate(op.arg)
     pattern = translate(op.substr)
 
-    if op.start is not None:
-        raise NotImplementedError("`start` not yet implemented")
-
-    if op.end is not None:
-        raise NotImplementedError("`end` not yet implemented")
+    if (op_start := op.start) is not None:
+        sub_string = ops.Substring(op.arg, op_start)
+        arg = translate(sub_string)
+        pos = df.functions.strpos(arg, pattern)
+        start = translate(op_start)
+        return df.functions.coalesce(
+            df.functions.nullif(pos + start, start), df.lit(0)
+        ) - df.lit(1)
 
     return df.functions.strpos(arg, pattern) - df.lit(1)

ibis/backends/mysql/registry.py

@@ -20,7 +20,6 @@
 )
 from ibis.backends.base.sql.alchemy.geospatial import geospatial_supported
 from ibis.backends.base.sql.alchemy.registry import (
-    _gen_string_find,
     geospatial_functions,
 )
 
@@ -137,6 +136,17 @@ def _regex_extract(arg, pattern, index):
     )
 
 
+def _string_find(t, op):
+    arg = t.translate(op.arg)
+    substr = t.translate(op.substr)
+
+    if op_start := op.start:
+        start = t.translate(op_start)
+        return sa.func.locate(substr, arg, start) - 1
+
+    return sa.func.locate(substr, arg) - 1
+
+
 class _mysql_trim(GenericFunction):
     inherit_cache = True
 
@@ -164,7 +174,7 @@ def compiles_mysql_trim(element, compiler, **kw):
         # static checks are not happy with using "if" as a property
         ops.Where: fixed_arity(getattr(sa.func, 'if'), 3),
         # strings
-        ops.StringFind: _gen_string_find(sa.func.locate),
+        ops.StringFind: _string_find,
         ops.FindInSet: (
             lambda t, op: (
                 sa.func.find_in_set(

ibis/backends/tests/test_string.py

@@ -415,6 +415,15 @@ def test_string_col_is_unicode(alltypes, df):
             id='find',
             marks=pytest.mark.notimpl(["polars"], raises=com.OperationNotDefinedError),
         ),
+        param(
+            lambda t: t.date_string_col.find('13', 3),
+            lambda t: t.date_string_col.str.find('13', 3),
+            id='find_start',
+            marks=[
+                pytest.mark.notimpl(["polars"], raises=com.OperationNotDefinedError),
+                pytest.mark.notyet(["bigquery"], raises=NotImplementedError),
+            ],
+        ),
         param(
             lambda t: t.string_col.lpad(10, 'a'),
             lambda t: t.string_col.str.pad(10, fillchar='a', side='left'),