Merge pull request #2232 from alixander/bad-latex

d2parser: escape backslashes for latex

ci/release/changelogs/next.md

@@ -7,6 +7,9 @@
 
 - Composition: links pointing to own board are purged [#2203](https://github.com/terrastruct/d2/pull/2203)
 - Syntax: reserved keywords must be unquoted [#2231](https://github.com/terrastruct/d2/pull/2231)
+- Latex: Backslashes in Latex blocks do not escape [#2232](https://github.com/terrastruct/d2/pull/2232)
+  - This is a breaking change. Previously Latex blocks required escaping the backslash. So
+    for older D2 versions, you should remove the excess backslashes.
 
 #### Bugfixes ⛑️
 

d2parser/parse.go

@@ -1480,6 +1480,12 @@ func (p *parser) parseBlockString() *d2ast.BlockString {
 		}
 
 		if r != endHint {
+			if (bs.Tag == "latex" || bs.Tag == "tex") && r == '\\' {
+				// For LaTeX, where single backslash is common, we escape it so that users don't have to write double the backslashes
+				sb.WriteRune('\\')
+				sb.WriteRune('\\')
+				continue
+			}
 			sb.WriteRune(r)
 			continue
 		}

e2etests/stable_test.go

@@ -1381,30 +1381,24 @@ c: |md
 		{
 			name: "latex",
 			script: `a: |latex
-\\Huge{\\frac{\\alpha g^2}{\\omega^5} e^{[ -0.74\\bigl\\{\\frac{\\omega U_\\omega 19.5}{g}\\bigr\\}^{\\!-4}\\,]}}
+\Huge{\frac{\alpha g^2}{\omega^5} e^{[ -0.74\bigl\{\frac{\omega U_\omega 19.5}{g}\bigr\}^{\!-4}\,]}}
 |
-
 b: |latex
 e = mc^2
 |
-
 z: |latex
-gibberish\\; math:\\sum_{i=0}^\\infty i^2
+gibberish\; math:\sum_{i=0}^\infty i^2
 |
-
 z -> a
 z -> b
-
 a -> c
 b -> c
 sugar -> c
 c: mixed together
-
 c -> solution: we get
-
 Linear program: {
   formula: |latex
-    \\min_{ \\mathclap{\\substack{ x \\in \\mathbb{R}^n \\ x \\geq 0 \\ Ax \\leq b }}} c^T x
+    \min_{ \mathclap{\substack{ x \in \mathbb{R}^n \ x \geq 0 \ Ax \leq b }}} c^T x
   |
 }
 `,

e2etests/testdata/files/grid_outside_labels.d2

@@ -4,61 +4,55 @@ container: ___________________________________container_________________________
 
   amscd plugin: {
     ex: |tex
-      \\begin{CD} B @>{\\text{very long label}}>> C S^{{\\mathcal{W}}_\\Lambda}\\otimes T @>j>> T\\\\ @VVV V \\end{CD}
+      \begin{CD} B @>{\text{very long label}}>> C S^{{\mathcal{W}}_\Lambda}\otimes T @>j>> T\\ @VVV V \end{CD}
     |
   }
 
   braket plugin: {
     style.3d: true
     ex: |tex
-      \\bra{a}\\ket{b}
+      \bra{a}\ket{b}
     |
   }
 
   cancel plugin: {
     ex: |tex
-      \\cancel{Culture + 5}
+      \cancel{Culture + 5}
     |
   }
-
   color plugin: {
     icon: https://icons.terrastruct.com/essentials/profits.svg
     icon.near: outside-right-center
     ex: |tex
-      \\textcolor{red}{y} = \\textcolor{green}{\\sin} x
+      \textcolor{red}{y} = \textcolor{green}{\sin} x
     |
   }
-
   gensymb plugin: {
     ex: |tex
-      \\lambda = 10.6\\,\\micro\\mathrm{m}
+      \lambda = 10.6\,\micro\mathrm{m}
     |
   }
-
   mhchem plugin: {
     style.multiple: true
     ex: |tex
       \ce{SO4^2- + Ba^2+ -> BaSO4 v}
     |
   }
-
   physics plugin: {
     ex: |tex
-      \\var{F[g(x)]}
-      \\dd(\\cos\\theta)
+      \var{F[g(x)]}
+      \dd(\cos\theta)
     |
   }
-
   multilines: {
     ex: |tex
-      \\displaylines{x = a + b \\\\ y = b + c}
-      \\sum_{k=1}^{n} h_{k} \\int_{0}^{1} \\bigl(\\partial_{k} f(x_{k-1}+t h_{k} e_{k}) -\\partial_{k} f(a)\\bigr) \\,dt
+      \displaylines{x = a + b \\ y = b + c}
+      \sum_{k=1}^{n} h_{k} \int_{0}^{1} \bigl(\partial_{k} f(x_{k-1}+t h_{k} e_{k}) -\partial_{k} f(a)\bigr) \,dt
     |
   }
-
   asm: {
     ex: |latex
-      \\min_{ \\mathclap{\\substack{ x \\in \\mathbb{R}^n \\ x \\geq 0 \\ Ax \\leq b }}} c^T x
+      \min_{ \mathclap{\substack{ x \in \mathbb{R}^n \ x \geq 0 \ Ax \leq b }}} c^T x
     |
   }
 }

e2etests/testdata/files/grid_with_latex.d2

@@ -19,7 +19,7 @@ y: {
 z: {
   grid-columns: 2
   lim: |latex
-    \\lim_{h \\rightarrow 0 } \\frac{f(x+h)-f(x)}{h}
+    \lim_{h \rightarrow 0 } \frac{f(x+h)-f(x)}{h}
   |
   add: |latex
     1 + 1