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2026-07-13 13:00:08 +08:00

406 行
11 KiB
Go

此文件含有模棱两可的 Unicode 字符
此文件含有可能会与其他字符混淆的 Unicode 字符。 如果您是想特意这样的,可以安全地忽略该警告。 使用 Escape 按钮显示他们。
package cli
import (
"strings"
"unicode/utf8"
)
// latexToUnicode renders a LaTeX math expression as a best-effort Unicode
// approximation suitable for a terminal: Greek letters, operators/relations,
// super/subscripts, \frac, \sqrt and accents map to real glyphs; anything it
// can't represent degrades to a readable plain-text form. There is no Go
// library for this, so the symbol table below is maintained by hand.
func latexToUnicode(expr string) string {
return convertMath([]rune(expr))
}
func convertMath(rs []rune) string {
var b strings.Builder
b.Grow(len(rs))
for i := 0; i < len(rs); {
switch r := rs[i]; r {
case '\\':
i = convertCommand(&b, rs, i)
case '^':
arg, ni := readAtom(rs, i+1, false)
b.WriteString(superscript(convertMath([]rune(arg))))
i = ni
case '_':
arg, ni := readAtom(rs, i+1, false)
b.WriteString(subscript(convertMath([]rune(arg))))
i = ni
case '{', '}':
i++
case '&', '~':
b.WriteByte(' ')
i++
case '$':
i++
default:
b.WriteRune(r)
i++
}
}
return b.String()
}
// convertCommand consumes the backslash command starting at rs[i] and writes
// its rendering; it returns the index just past everything it consumed.
func convertCommand(b *strings.Builder, rs []rune, i int) int {
j := i + 1
if j >= len(rs) {
return j
}
if !isASCIILetter(rs[j]) {
switch ch := rs[j]; ch {
case '\\':
b.WriteString(" ")
case ',', ';', ':', '!', ' ':
b.WriteByte(' ')
default:
b.WriteRune(ch)
}
return j + 1
}
k := j
for k < len(rs) && isASCIILetter(rs[k]) {
k++
}
cmd := string(rs[j:k])
switch cmd {
case "frac", "tfrac", "dfrac":
num, k2 := readAtom(rs, k, true)
den, k3 := readAtom(rs, k2, true)
b.WriteString(renderFrac(convertMath([]rune(num)), convertMath([]rune(den))))
return k3
case "sqrt":
idx := ""
if k < len(rs) && rs[k] == '[' {
idx, k = readBracket(rs, k)
}
arg, k2 := readAtom(rs, k, true)
b.WriteString(renderSqrt(idx, convertMath([]rune(arg))))
return k2
case "text", "textrm", "textbf", "textit", "mathrm", "mathsf", "mathtt", "mathit", "mathbf", "mathcal", "operatorname":
arg, k2 := readAtom(rs, k, true)
b.WriteString(arg)
return k2
case "mathbb":
arg, k2 := readAtom(rs, k, true)
b.WriteString(blackboard(arg))
return k2
case "left", "right", "big", "Big", "bigg", "Bigg", "bigl", "bigr", "Bigl", "Bigr", "displaystyle", "textstyle", "limits", "nolimits":
return k
case "begin", "end":
_, k2 := readAtom(rs, k, true)
return k2
}
if combining, ok := accents[cmd]; ok {
arg, k2 := readAtom(rs, k, true)
b.WriteString(applyCombining(convertMath([]rune(arg)), combining))
return k2
}
if sym, ok := symbols[cmd]; ok {
b.WriteString(sym)
return k
}
b.WriteString(cmd)
return k
}
// readAtom reads the argument of a command or script: a {balanced group}, a
// \command, or a single rune. Returns the inner text (no surrounding braces)
// and the index just past it.
func readAtom(rs []rune, i int, skipSpaces bool) (string, int) {
if skipSpaces {
for i < len(rs) && rs[i] == ' ' {
i++
}
}
if i >= len(rs) {
return "", i
}
switch rs[i] {
case '{':
depth := 0
start := i + 1
for j := i; j < len(rs); j++ {
switch rs[j] {
case '{':
depth++
case '}':
depth--
if depth == 0 {
return string(rs[start:j]), j + 1
}
}
}
return string(rs[start:]), len(rs)
case '\\':
k := i + 1
if k < len(rs) && !isASCIILetter(rs[k]) {
return string(rs[i : k+1]), k + 1
}
for k < len(rs) && isASCIILetter(rs[k]) {
k++
}
return string(rs[i:k]), k
default:
return string(rs[i]), i + 1
}
}
func readBracket(rs []rune, i int) (string, int) {
start := i + 1
for j := start; j < len(rs); j++ {
if rs[j] == ']' {
return string(rs[start:j]), j + 1
}
}
return "", len(rs)
}
func renderFrac(num, den string) string {
return wrapIfCompound(num) + "/" + wrapIfCompound(den)
}
func renderSqrt(idx, arg string) string {
if utf8.RuneCountInString(arg) > 1 {
arg = "(" + arg + ")"
}
switch idx {
case "", "2":
return "√" + arg
case "3":
return "∛" + arg
case "4":
return "∜" + arg
}
return superscript(idx) + "√" + arg
}
func wrapIfCompound(s string) string {
if utf8.RuneCountInString(s) > 1 {
return "(" + s + ")"
}
return s
}
func applyCombining(s string, mark rune) string {
rs := []rune(s)
if len(rs) == 0 {
return string(mark)
}
return string(rs[0]) + string(mark) + string(rs[1:])
}
func blackboard(s string) string {
var b strings.Builder
for _, r := range s {
if bb, ok := blackboardCaps[r]; ok {
b.WriteRune(bb)
} else {
b.WriteRune(r)
}
}
return b.String()
}
func superscript(s string) string {
if t, ok := mapAll(s, superMap); ok {
return t
}
if utf8.RuneCountInString(s) == 1 {
return "^" + s
}
return "^(" + s + ")"
}
func subscript(s string) string {
if t, ok := mapAll(s, subMap); ok {
return t
}
if utf8.RuneCountInString(s) == 1 {
return "_" + s
}
return "_(" + s + ")"
}
func mapAll(s string, m map[rune]rune) (string, bool) {
if s == "" {
return "", true
}
var b strings.Builder
for _, r := range s {
c, ok := m[r]
if !ok {
return "", false
}
b.WriteRune(c)
}
return b.String(), true
}
func isASCIILetter(r rune) bool {
return (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z')
}
// normalizeMath rewrites the alternate math delimiters \(..\) and \[..\] to
// $..$ / $$..$$ and collapses newlines inside a $$ display block onto one line
// so the inline math parser sees a single contiguous run. It tracks fenced and
// inline code so literal delimiters inside code are never rewritten.
func normalizeMath(s string) string {
rs := []rune(s)
n := len(rs)
var b strings.Builder
b.Grow(len(s))
inFenced, inCode, inDisplay := false, false, false
for i := 0; i < n; {
r := rs[i]
if r == '`' && i+2 < n && rs[i+1] == '`' && rs[i+2] == '`' {
inFenced = !inFenced
b.WriteString("```")
i += 3
continue
}
if r == '`' && !inFenced {
inCode = !inCode
b.WriteRune(r)
i++
continue
}
if inFenced || inCode {
b.WriteRune(r)
i++
continue
}
if r == '\\' && i+1 < n {
switch rs[i+1] {
case '\\':
b.WriteString("\\\\")
i += 2
continue
case '[':
b.WriteString("$$")
inDisplay = true
i += 2
continue
case ']':
b.WriteString("$$")
inDisplay = false
i += 2
continue
case '(':
b.WriteString("$")
i += 2
continue
case ')':
b.WriteString("$")
i += 2
continue
}
}
if r == '$' && i+1 < n && rs[i+1] == '$' {
b.WriteString("$$")
inDisplay = !inDisplay
i += 2
continue
}
if r == '\n' && inDisplay {
b.WriteByte(' ')
i++
continue
}
b.WriteRune(r)
i++
}
return b.String()
}
var symbols = map[string]string{
"alpha": "α", "beta": "β", "gamma": "γ", "delta": "δ", "epsilon": "ε",
"varepsilon": "ε", "zeta": "ζ", "eta": "η", "theta": "θ", "vartheta": "ϑ",
"iota": "ι", "kappa": "κ", "lambda": "λ", "mu": "μ", "nu": "ν", "xi": "ξ",
"omicron": "ο", "pi": "π", "varpi": "ϖ", "rho": "ρ", "varrho": "ϱ",
"sigma": "σ", "varsigma": "ς", "tau": "τ", "upsilon": "υ", "phi": "φ",
"varphi": "ϕ", "chi": "χ", "psi": "ψ", "omega": "ω",
"Gamma": "Γ", "Delta": "Δ", "Theta": "Θ", "Lambda": "Λ", "Xi": "Ξ",
"Pi": "Π", "Sigma": "Σ", "Upsilon": "Υ", "Phi": "Φ", "Psi": "Ψ", "Omega": "Ω",
"times": "×", "div": "÷", "cdot": "·", "ast": "", "star": "⋆",
"pm": "±", "mp": "∓", "oplus": "⊕", "ominus": "⊖", "otimes": "⊗",
"oslash": "⊘", "odot": "⊙", "circ": "∘", "bullet": "•", "setminus": "",
"leq": "≤", "le": "≤", "geq": "≥", "ge": "≥", "neq": "≠", "ne": "≠",
"equiv": "≡", "approx": "≈", "cong": "≅", "sim": "", "simeq": "≃",
"propto": "∝", "ll": "≪", "gg": "≫", "doteq": "≐", "asymp": "≍",
"leftarrow": "←", "rightarrow": "→", "to": "→", "gets": "←",
"leftrightarrow": "↔", "Leftarrow": "⇐", "Rightarrow": "⇒",
"Leftrightarrow": "⇔", "implies": "⇒", "iff": "⇔", "mapsto": "↦",
"uparrow": "↑", "downarrow": "↓", "longrightarrow": "⟶", "longleftarrow": "⟵",
"sum": "∑", "prod": "∏", "coprod": "∐", "int": "∫", "iint": "∬",
"iiint": "∭", "oint": "∮", "nabla": "∇", "partial": "∂",
"infty": "∞", "sqrt": "√", "surd": "√",
"in": "∈", "notin": "∉", "ni": "∋", "subset": "⊂", "supset": "⊃",
"subseteq": "⊆", "supseteq": "⊇", "cup": "", "cap": "∩",
"emptyset": "∅", "varnothing": "∅", "forall": "∀", "exists": "∃",
"nexists": "∄", "neg": "¬", "lnot": "¬", "land": "∧", "wedge": "∧",
"lor": "", "vee": "",
"angle": "∠", "perp": "⊥", "parallel": "∥", "mid": "", "nmid": "∤",
"triangle": "△", "square": "□", "diamond": "◇", "top": "", "bot": "⊥",
"vdash": "⊢", "models": "⊨", "therefore": "∴", "because": "∵",
"ldots": "…", "dots": "…", "cdots": "⋯", "vdots": "⋮", "ddots": "⋱",
"prime": "", "degree": "°", "deg": "°", "hbar": "ℏ", "ell": "",
"Re": "", "Im": "", "aleph": "ℵ", "wp": "℘",
"langle": "⟨", "rangle": "⟩", "lceil": "⌈", "rceil": "⌉",
"lfloor": "⌊", "rfloor": "⌋", "backslash": "\\",
"quad": " ", "qquad": " ", "space": " ", "thinspace": " ",
"lim": "lim", "sin": "sin", "cos": "cos", "tan": "tan", "log": "log",
"ln": "ln", "exp": "exp", "min": "min", "max": "max", "det": "det",
"gcd": "gcd", "dim": "dim", "ker": "ker",
}
var accents = map[string]rune{
"hat": '̂', "widehat": '̂', "bar": '̄', "overline": '̄',
"vec": '⃗', "dot": '̇', "ddot": '̈', "tilde": '̃',
"widetilde": '̃', "acute": '́', "grave": '̀', "check": '̌',
}
var superMap = map[rune]rune{
'0': '⁰', '1': '¹', '2': '²', '3': '³', '4': '⁴', '5': '⁵', '6': '⁶',
'7': '⁷', '8': '⁸', '9': '⁹', '+': '⁺', '-': '⁻', '=': '⁼', '(': '⁽',
')': '⁾', 'a': 'ᵃ', 'b': 'ᵇ', 'c': 'ᶜ', 'd': 'ᵈ', 'e': 'ᵉ', 'f': 'ᶠ',
'g': 'ᵍ', 'h': 'ʰ', 'i': 'ⁱ', 'j': 'ʲ', 'k': 'ᵏ', 'l': 'ˡ', 'm': 'ᵐ',
'n': 'ⁿ', 'o': 'ᵒ', 'p': 'ᵖ', 'r': 'ʳ', 's': 'ˢ', 't': 'ᵗ', 'u': 'ᵘ',
'v': 'ᵛ', 'w': 'ʷ', 'x': 'ˣ', 'y': 'ʸ', 'z': 'ᶻ',
}
var subMap = map[rune]rune{
'0': '₀', '1': '₁', '2': '₂', '3': '₃', '4': '₄', '5': '₅', '6': '₆',
'7': '₇', '8': '₈', '9': '₉', '+': '₊', '-': '₋', '=': '₌', '(': '₍',
')': '₎', 'a': 'ₐ', 'e': 'ₑ', 'h': 'ₕ', 'i': 'ᵢ', 'j': 'ⱼ', 'k': 'ₖ',
'l': 'ₗ', 'm': 'ₘ', 'n': 'ₙ', 'o': 'ₒ', 'p': 'ₚ', 'r': 'ᵣ', 's': 'ₛ',
't': 'ₜ', 'u': 'ᵤ', 'v': 'ᵥ', 'x': 'ₓ',
}
var blackboardCaps = map[rune]rune{
'A': '𝔸', 'B': '𝔹', 'C': '', 'D': '𝔻', 'E': '𝔼', 'F': '𝔽', 'G': '𝔾',
'H': '', 'I': '𝕀', 'J': '𝕁', 'K': '𝕂', 'L': '𝕃', 'M': '𝕄', 'N': '',
'O': '𝕆', 'P': '', 'Q': '', 'R': '', 'S': '𝕊', 'T': '𝕋', 'U': '𝕌',
'V': '𝕍', 'W': '𝕎', 'X': '𝕏', 'Y': '𝕐', 'Z': '',
}