Merge pull request #75 from lambda-feedback/tr111-improve-input-sanitisation-handwritten-preview

Added input sanitisation that removes \mathrm and \text from handwrit…

Author: KarlLundengaard

app/preview.py

@@ -36,6 +36,40 @@ class Preview(TypedDict):
 class Result(TypedDict):
     preview: Preview
 
+def find_matching_parenthesis(string, index, delimiters=None):
+    depth = 0
+    if delimiters == None:
+        delimiters = ('(', ')')
+    for k in range(index, len(string)):
+        if string[k] == delimiters[0]:
+            depth += 1
+            continue
+        if string[k] == delimiters[1]:
+            depth += -1
+            if depth == 0:
+                return k
+    return -1
+
+def sanitise_latex(response):
+    response = "".join(response.split())
+    response = response.replace('~',' ')
+    wrappers = [r"\mathrm",r"\text"]
+    for wrapper in wrappers:
+        processed_response = []
+        index = 0
+        while index < len(response):
+            wrapper_start = response.find(wrapper+"{", index)
+            if wrapper_start > -1:
+                processed_response.append(response[index:wrapper_start])
+                wrapper_end = find_matching_parenthesis(response, wrapper_start+1, delimiters=('{','}'))
+                inside_wrapper = response[(wrapper_start+len(wrapper+"{")):wrapper_end]
+                processed_response.append(inside_wrapper)
+                index = wrapper_end+1
+            else:
+                processed_response.append(response[index:])
+                index = len(response)
+        response = "".join(processed_response)
+    return response
 
 def parse_latex(response: str, symbols: SymbolDict) -> str:
     """Parse a LaTeX string to a sympy string while preserving custom symbols.
@@ -53,6 +87,8 @@ def parse_latex(response: str, symbols: SymbolDict) -> str:
     """
     substitutions = {}
 
+    response = sanitise_latex(response)
+
     for sympy_symbol_str in symbols:
         symbol_str = symbols[sympy_symbol_str]["latex"]
         latex_symbol_str = extract_latex(symbol_str)
@@ -78,7 +114,6 @@ def parse_latex(response: str, symbols: SymbolDict) -> str:
     except Exception as e:
         raise ValueError(str(e))
 
-
 def parse_symbolic(response: str, params):
     response_list_in = create_expression_set(response, params)
     response_list_out = []

app/preview_tests.py

@@ -127,26 +127,6 @@ def test_sympy_conversion_preserves_default_symbols(self):
         preview = result["preview"]
         assert preview.get("latex") == "\\mu + x + 1"
 
-    def test_latex_conversion_preserves_optional_symbols(self):
-        response = "m_{ \\text{table} } + \\text{hello}_\\text{world} - x + 1"
-        params = Params(
-            is_latex=True,
-            simplify=False,
-            symbols={
-                "m_table": {
-                    "latex": r"hello \( m_{\text{table}} \) world",
-                    "aliases": [],
-                },
-                "test": {
-                    "latex": r"hello $ \text{hello}_\text{world} $ world.",
-                    "aliases": [],
-                },
-            },
-        )
-        result = preview_function(response, params)
-        preview = result["preview"]
-        assert preview.get("sympy") == "m_table + test - x + 1"
-
     def test_sympy_conversion_preserves_optional_symbols(self):
         response = "m_table + test + x + 1"
         params = Params(