Allow skipping numbering for lines

Closes #10

equate/src/equate.typ

@@ -190,12 +190,24 @@
     })
     .map(((i, _)) => i)
 
+  // Indices of lines that are marked not to be numbered.
+  let revoked = lines
+    .enumerate()
+    .filter(((i, line)) => {
+      if i not in labelled { return false }
+      return line.last().text == "<equate:revoke>"
+    })
+    .map(((i, _)) => i)
+
+  // The "revoke" label shall not count as a labelled line.
+  labelled = labelled.filter(i => i not in revoked)
+
   // Indices of numbered lines in this equation.
   let numbered = if number-mode == "line" {
-    range(lines.len())
+    range(lines.len()).filter(i => i not in revoked)
   } else if labelled.len() == 0 and has-label {
     // Only outer label, so number all lines.
-    range(lines.len())
+    range(lines.len()).filter(i => i not in revoked)
   } else {
     labelled
   }
@@ -204,6 +216,13 @@
     numbered,
     lines.enumerate()
       .map(((i, line)) => {
+        if i in revoked {
+          // Remove "revoke" label and space and return line.
+          line.remove(-1)
+          if line.at(-2, default: none) == [ ] { line.remove(-2) }
+          return line
+        }
+
         if i not in labelled { return line }
 
         // Remove trailing spacing (before label).

equate/tests/number-mode/test.typ

@@ -27,6 +27,10 @@ $ q + r #<label> \
 $ u + v \
   w + x $ <equate:revoke>
 
+$ y + z \
+  1 + 2 #<equate:revoke> \
+  3 + 4 $ <label>
+
 #show: equate.with(sub-numbering: true, number-mode: "label")
 
 #set math.equation(numbering: "(1.1)")
@@ -50,3 +54,7 @@ $ q + r #<label> \
 
 $ u + v \
   w + x $ <equate:revoke>
+
+$ y + z \
+  1 + 2 #<equate:revoke> \
+  3 + 4 $ <label>

equate/tests/numbering/test.typ

@@ -22,6 +22,10 @@ $ i + j \
 $ m + n \
   o + p $ <equate:revoke>
 
+$ q + r \
+  s + t #<equate:revoke> \
+  u + v $
+
 #show: equate.with(sub-numbering: true)
 
 #set math.equation(numbering: "(1.1)")
@@ -40,3 +44,7 @@ $ i + j \
 
 $ m + n \
   o + p $ <equate:revoke>
+
+$ q + r \
+  s + t #<equate:revoke> \
+  u + v $