feat: show math in plain text in library cards

openedx/core/djangoapps/content/search/documents.py

@@ -14,6 +14,7 @@
 from rest_framework.exceptions import NotFound
 
 from openedx.core.djangoapps.content.search.models import SearchAccess
+from openedx.core.djangoapps.content.search.plain_text_math import process_mathjax
 from openedx.core.djangoapps.content_libraries import api as lib_api
 from openedx.core.djangoapps.content_tagging import api as tagging_api
 from openedx.core.djangoapps.xblock import api as xblock_api
@@ -220,7 +221,7 @@ class implementation returns only:
         # Generate description from the content
         description = _get_description_from_block_content(block_type, content_data)
         if description:
-            block_data[Fields.description] = description
+            block_data[Fields.description] = process_mathjax(description)
 
     except Exception as err:  # pylint: disable=broad-except
         log.exception(f"Failed to process index_dictionary for {block.usage_key}: {err}")

openedx/core/djangoapps/content/search/plain_text_math.py

@@ -0,0 +1,103 @@
+"""
+Helper class to convert mathjax equations to plain text.
+"""
+
+import re
+
+import unicodeit
+
+
+class PlainTextMath:
+    """
+    Converts mathjax equations to plain text using unicodeit and some preprocessing.
+    """
+    equation_pattern = re.compile(
+        r'\[mathjaxinline\](.*?)\[\/mathjaxinline\]|\[mathjax\](.*?)\[\/mathjax\]|\\\((.*?)\\\)|\\\[(.*?)\\\]'
+    )
+    eqn_replacements = (
+        # just remove prefix `\`
+        ("\\sin", "sin"),
+        ("\\cos", "cos"),
+        ("\\tan", "tan"),
+        ("\\arcsin", "arcsin"),
+        ("\\arccos", "arccos"),
+        ("\\arctan", "arctan"),
+        ("\\cot", "cot"),
+        ("\\sec", "sec"),
+        ("\\csc", "csc"),
+        # Is used for matching brackets in mathjax, should be required in plain text.
+        ("\\left", ""),
+        ("\\right", ""),
+    )
+    regex_replacements = (
+        (re.compile(r'\\mathbf{(.*?)}'), r"\1"),
+    )
+
+    def _fraction_handler(self, equation: str) -> str:
+        """
+        Converts `\\frac{x}{y}` to `(x/y)` while handling nested `{}`.
+
+        For example: `\\frac{2}{\\sqrt{1+y}}` is converted to `(2/\\sqrt{1+y})`.
+
+        Args:
+            equation: string
+
+        Returns:
+            String with `\\frac` replaced by normal `/` symbol.
+        """
+        start_index = equation.find("\\frac{")
+        if start_index == -1:
+            return equation
+        mid_index = equation.find("}{")
+        if mid_index == -1:
+            return equation
+
+        numerator = equation[start_index + 6:mid_index]
+        # shift mid_index by length of }{ chars i.e., 2
+        mid_index += 2
+        open_count = 0
+
+        for i, char in enumerate(equation[mid_index:]):
+            if char == "{":
+                open_count += 1
+            if char == "}":
+                if open_count == 0:
+                    break
+                open_count -= 1
+        else:
+            # Invalid `\frac` format
+            return equation
+
+        denominator = equation[mid_index:mid_index + i]
+        # Now re-create the equation with `(numerator / denominator)`
+        equation = equation[:start_index] + f"({numerator}/{denominator})" + equation[mid_index + i + 1:]
+        return equation
+
+    def _handle_replacements(self, equation: str) -> str:
+        """
+        Makes a bunch of replacements in equation string.
+        """
+        for q, replacement in self.eqn_replacements:
+            equation = equation.replace(q, replacement)
+        for pattern, replacement in self.regex_replacements:
+            equation = re.sub(pattern, replacement, equation)
+        return equation
+
+    def run(self, eqn_matches: re.Match) -> str:
+        """
+        Takes re.Match object and runs conversion process on each match group.
+        """
+        groups = eqn_matches.groups()
+        for group in groups:
+            if group:
+                group = self._fraction_handler(group)
+                group = self._handle_replacements(group)
+                return unicodeit.replace(group)
+        return None
+
+
+processor = PlainTextMath()
+
+
+def process_mathjax(content: str) -> str:
+    return re.sub(processor.equation_pattern, processor.run, content)

openedx/core/djangoapps/content/search/tests/test_documents.py

@@ -477,3 +477,81 @@ def test_collection_with_published_library(self):
                 "num_children": 1
             }
         }
+
+    def test_mathjax_plain_text_conversion_for_search(self):
+        """
+        Test how an HTML block with mathjax equations gets converted to plain text in search description.
+        """
+        # pylint: disable=line-too-long
+        block = BlockFactory.create(
+            parent_location=self.toy_course.location,
+            category="html",
+            display_name="Non-default HTML Block",
+            editor="raw",
+            use_latex_compiler=True,
+            data=(
+                "Simple addition: \\( 2 + 3 \\) |||"
+                " Simple subtraction: \\( 5 - 2 \\) |||"
+                " Simple multiplication: \\( 4 * 6 \\) |||"
+                " Simple division: \\( 8 / 2 \\) |||"
+                " Mixed arithmetic: \\( 2 + 3  4 \\) |||"
+                " Simple exponentiation: \\[ 2^3 \\] |||"
+                " Root extraction: \\[ 16^{1/2} \\] |||"
+                " Exponent with multiple terms: \\[ (2 + 3)^2 \\] |||"
+                " Nested exponents: \\[ 2^(3^2) \\] |||"
+                " Mixed roots: \\[ 8^{1/2}  3^2 \\] |||"
+                " Simple fraction: [mathjaxinline] 3/4 [/mathjaxinline] |||"
+                " Decimal to fraction conversion: [mathjaxinline] 0.75 = 3/4 [/mathjaxinline] |||"
+                " Mixed fractions: [mathjaxinline] 1 1/2 = 3/2 [/mathjaxinline] |||"
+                " Converting decimals to mixed fractions: [mathjaxinline] 2.5 = 5/2 [/mathjaxinline] |||"
+                " Sine, cosine, and tangent: [mathjaxinline] \\sin(x) [/mathjaxinline] [mathjaxinline] \\cos(x) [/mathjaxinline] [mathjaxinline] \\tan(x) [/mathjaxinline] |||"
+                " Trig identities: [mathjaxinline] \\sin(x + y) = \\sin(x)  \\cos(y) + \\cos(x)  \\sin(y) [/mathjaxinline] |||"
+                " Hyperbolic trig functions: [mathjaxinline] \\sinh(x) [/mathjaxinline] [mathjaxinline] \\cosh(x) [/mathjaxinline] |||"
+                " Simple derivative: [mathjax] f(x) = x^2, f'(x) = 2x [/mathjax] |||"
+                " Double integral: [mathjax] int\\int (x + y) dxdy [/mathjax] |||"
+                " Partial derivatives: [mathjax] f(x,y) = xy, \\frac{\\partial f}{\\partial x} = y [/mathjax] [mathjax] \\frac{\\partial f}{\\partial y} = x [/mathjax] |||"
+                " Mean and standard deviation: [mathjax] mu = 2, \\sigma = 1 [/mathjax] |||"
+                " Binomial probability: [mathjax] P(X = k) = (\\binom{n}{k} p^k (1-p)^{n-k}) [/mathjax] |||"
+                " Gaussian distribution: [mathjax] N(\\mu, \\sigma^2) [/mathjax] |||"
+                " Greek letters: [mathjaxinline] \\alpha [/mathjaxinline] [mathjaxinline] \\beta [/mathjaxinline] [mathjaxinline] \\gamma [/mathjaxinline] |||"
+                " Subscripted variables: [mathjaxinline] x_i [/mathjaxinline] [mathjaxinline] y_j [/mathjaxinline] |||"
+                " Superscripted variables: [mathjaxinline] x^{i} [/mathjaxinline] |||"
+                " Not supported: \\( \\begin{bmatrix} 1 & 0 \\ 0 & 1 \\end{bmatrix} = I \\)"
+            ),
+        )
+        # pylint: enable=line-too-long
+        doc = {}
+        doc.update(searchable_doc_for_course_block(block))
+        doc.update(searchable_doc_tags(block.usage_key))
+        expected_equations = [
+            'Simple addition:  2 + 3',
+            'Simple subtraction:  5 − 2',
+            'Simple multiplication:  4 * 6',
+            'Simple division:  8 / 2',
+            'Mixed arithmetic:  2 + 3 4',
+            'Simple exponentiation:  2³',
+            'Root extraction:  16¹^/²',
+            'Exponent with multiple terms:  (2 + 3)²',
+            'Nested exponents:  2⁽3²)',
+            'Mixed roots:  8¹^/² 3²',
+            'Simple fraction:  3/4',
+            'Decimal to fraction conversion:  0.75 = 3/4',
+            'Mixed fractions:  1 1/2 = 3/2',
+            'Converting decimals to mixed fractions:  2.5 = 5/2',
+            'Sine, cosine, and tangent:  sin(x)   cos(x)   tan(x)',
+            'Trig identities:  sin(x + y) = sin(x) cos(y) + cos(x) sin(y)',
+            'Hyperbolic trig functions:  sinh(x)   cosh(x)',
+            "Simple derivative:  f(x) = x², f'(x) = 2x",
+            'Double integral:  int∫ (x + y) dxdy',
+            'Partial derivatives:  f(x,y) = xy, (∂ f/∂ x) = y   (∂ f/∂ y) = x',
+            'Mean and standard deviation:  mu = 2, σ = 1',
+            'Binomial probability:  P(X = k) = (\\binom{n}{k} pᵏ (1−p)ⁿ⁻ᵏ)',
+            'Gaussian distribution:  N(μ, σ²)',
+            'Greek letters:  α   β   γ',
+            'Subscripted variables:  xᵢ   yⱼ',
+            'Superscripted variables:  xⁱ',
+            'Not supported:  \\begin{bmatrix} 1 & 0 \\ 0 & 1 \\end{bmatrix} = I',
+        ]
+        eqns = doc['description'].split('|||')
+        for i, eqn in enumerate(eqns):
+            assert eqn.strip() == expected_equations[i]

requirements/edx/base.txt

@@ -1235,6 +1235,8 @@ unicodecsv==0.14.1
     # via
     #   -r requirements/edx/kernel.in
     #   edx-enterprise
+unicodeit==0.7.5
+    # via -r requirements/edx/kernel.in
 uritemplate==4.1.1
     # via
     #   drf-spectacular

requirements/edx/development.txt

@@ -2178,6 +2178,10 @@ unicodecsv==0.14.1
     #   -r requirements/edx/doc.txt
     #   -r requirements/edx/testing.txt
     #   edx-enterprise
+unicodeit==0.7.5
+    # via
+    #   -r requirements/edx/doc.txt
+    #   -r requirements/edx/testing.txt
 unidiff==0.7.5
     # via -r requirements/edx/testing.txt
 uritemplate==4.1.1

requirements/edx/doc.txt

@@ -1530,6 +1530,8 @@ unicodecsv==0.14.1
     # via
     #   -r requirements/edx/base.txt
     #   edx-enterprise
+unicodeit==0.7.5
+    # via -r requirements/edx/base.txt
 uritemplate==4.1.1
     # via
     #   -r requirements/edx/base.txt

requirements/edx/kernel.in

@@ -161,3 +161,4 @@ webob
 web-fragments                       # Provides the ability to render fragments of web pages
 XBlock[django]                      # Courseware component architecture
 xss-utils                           # https://github.com/openedx/edx-platform/pull/20633 Fix XSS via Translations
+unicodeit                           # Converts mathjax equation to plain text by using unicode symbols

requirements/edx/testing.txt

@@ -1612,6 +1612,8 @@ unicodecsv==0.14.1
     # via
     #   -r requirements/edx/base.txt
     #   edx-enterprise
+unicodeit==0.7.5
+    # via -r requirements/edx/base.txt
 unidiff==0.7.5
     # via -r requirements/edx/testing.in
 uritemplate==4.1.1