Math expressions

[T8RIN]

Is it possible to parse math expressions in markdown, like \(a \times b\)

[T8RIN]

i solved by doing this, but looks ugly

fun String.replaceCodeMarkdown(): String =
    replace("```", "`")
        .replaceFractions()
        .replaceSqrt()
        .replaceMathBBToSymbol()
        .let {
            mathPairs.fold(it) { acc, (pattern, char) ->
                acc.replace(pattern, mathString(char))
            }
        }

private fun mathString(string: String) = string

private fun String.replaceFractions(): String {
    val fraction = Regex("\\\\frac\\{([^}]*)\\}\\{([^}]*)\\}")
    return fraction.replace(this) { matchResult ->
        val numerator = matchResult.groupValues[1]
        val denominator = matchResult.groupValues[2]
        mathString("$numerator/$denominator")
    }
}

private fun String.replaceMathBBToSymbol(): String {
    val replacementMap = mapOf(
        "A" to "𝔸", "B" to "𝔹", "C" to "ℂ", "D" to "𝔻", "E" to "𝔼",
        "F" to "𝔽", "G" to "𝔾", "H" to "ℍ", "I" to "𝕀", "J" to "𝕁",
        "K" to "𝕂", "L" to "𝕃", "M" to "𝕄", "N" to "ℕ", "O" to "𝕆",
        "P" to "ℙ", "Q" to "ℚ", "R" to "ℝ", "S" to "𝕊", "T" to "𝕋",
        "U" to "𝕌", "V" to "𝕍", "W" to "𝕎", "X" to "𝕏", "Y" to "𝕐",
        "Z" to "ℤ"
    )

    val regex = Regex("\\\\mathbb\\{([A-Za-z])\\}")

    return regex.replace(this) { matchResult ->
        val letter = matchResult.groupValues[1].uppercase()[0].toString()
        replacementMap[letter] ?: letter
    }
}

private fun String.replaceSqrt(): String {
    val sqrt = Regex("\\\\sqrt(?:\\[([^]]+)])?\\{([^}]*)\\}")

    return sqrt.replace(this) { matchResult ->
        val n = matchResult.groupValues[1].takeIf { it.isNotEmpty() }?.toIntOrNull()
        val x = matchResult.groupValues[2]

        mathString(n?.let { "(${n})√$x" } ?: "√$x")
    }
}

private val mathPairs by lazy {
    listOf(
        "\\(" to "(",
        "\\)" to ")",
        "\\[" to "[",
        "\\[" to "]",
        "\\quad" to "  ",
        "\\neg" to "¬",
        "\\pm" to "±",
        "\\mp" to "∓",
        "\\div" to "÷",
        "\\%" to "%",
        "\\oplus" to "⊕",
        "\\otimes" to "⊗",
        "\\odot" to "⊙",
        "\\setminus" to "∖",
        "\\int!!!int!!!int" to "∭",
        "\\int!!!int" to "∬",
        "\\int" to "∫",
        "\\cdot" to "·",
        "\\to" to "→",
        "\\infty" to "∞",
        "\\Rightarrow" to "⇒",
        "\\Leftrightarrow" to "⇔",
        "\\forall" to "∀",
        "\\partial" to "∂",
        "\\exists" to "∃",
        "\\emptyset" to "∅",
        "\\nabla" to "∇",
        "\\in" to "∈",
        "\\not\\in" to "∉",
        "\\notin" to "∉",
        "\\prod" to "∏",
        "\\sum" to "∑",
        "\\surd" to "√",
        "\\wedge" to "∧",
        "\\land" to "∧",
        "\\vee" to "∨",
        "\\lor" to "∨",
        "\\lnot" to "!",
        "\\cap" to "∩",
        "\\cup" to "∪",
        "\\int" to "∫",
        "\\approx" to "≈",
        "\\neq" to "≠",
        "\\equiv" to "≡",
        "\\leq" to "≤",
        "\\geq" to "≥",
        "\\subseteq" to "⊆",
        "\\subsetneq" to "⊊",
        "\\supseteq" to "⊇",
        "\\supsetneq" to "⊋",
        "\\subset" to "⊂",
        "\\supset" to "⊃",
        "^\\circ" to "°",
        "\\times" to "×",
        "\\lfloor" to "⌊",
        "\\rfloor" to "⌋",
        "\\lceil" to "⌈",
        "\\rceil" to "⌉",
        "\\nexists" to "∅",
        "\\Delta" to "Δ",
        "\\sphericalangle" to "∢",
        "\\measuredangle" to "∡",
        "\\angle" to "∠",
        "\\cong" to "≅",
        "\\widehat" to "◡",
        "\\parallel" to "∥",
        "\\perp" to "⊥",
        "\\triangle" to "△",
        "\\sim" to "∼",
        "\\overline" to "",
        "\\overrightarrow" to "",
        "\\aleph_0" to "ℵ",
        "\\alpha" to "α",
        "\\kappa" to "κ",
        "\\psi" to "ψ",
        "\\digamma" to "z",
        "\\Delta" to "∆",
        "\\Theta" to "Θ",
        "\\beta" to "β",
        "\\lambda" to "λ",
        "\\rho" to "ρ",
        "\\varepsilon" to "ε",
        "\\Gamma" to "Γ",
        "\\Upsilon" to "Υ",
        "\\chi" to "χ",
        "\\mu" to "µ",
        "\\sigma" to "σ",
        "\\varkappa" to "κ",
        "\\Lambda" to "Λ",
        "\\Xi" to "Ξ",
        "\\delta" to "δ",
        "\\nu" to "ν",
        "\\tau" to "τ",
        "\\varphi" to "φ",
        "\\Omega" to "Ω",
        "\\epsilon" to "ε",
        "\\theta" to "θ",
        "\\varpi" to "π",
        "\\Phi" to "Φ",
        "\\aleph" to "ℵ",
        "\\eta" to "η",
        "\\omega" to "ω",
        "\\upsilon" to "υ",
        "\\varrho" to "ρ",
        "\\Pi" to "Π",
        "\\gamma" to "γ",
        "\\phi" to "φ",
        "\\xi" to "ξ",
        "\\varsigma" to "ς",
        "\\Psi" to "Ψ",
        "\\iota" to "ι",
        "\\pi" to "π",
        "\\zeta" to "ζ",
        "\\vartheta" to "ϑ",
        "\\Sigma" to "Σ"
    )
}

[MohamedRejeb]

Hi, Thanks for creating this issue, I think that's an important feature to have, I will try to add it ASAP.

[T8RIN]

Thanks !