Printer: add space between + and ++ (#405)

Fixes #403 

Co-authored-by: Eldritch Conundrum <eldritch.conundrum@gmail.com>

src/printer.fs

@@ -128,11 +128,15 @@ type PrinterImpl(withLocations) =
             // Binary operators.
             | Op op, [a1; a2] ->
                 let prec = precedence.[op]
-                let res =
+                let e1, e2 =
                     if prec = precedence.["="] then // "=", "+=", or other operator with right-associativity
-                        out "%s%s%s" (exprToSLevel indent (prec+1) a1) op (exprToSLevel indent prec a2)
+                        (exprToSLevel indent (prec+1) a1), (exprToSLevel indent prec a2)
                     else
-                        out "%s%s%s" (exprToSLevel indent prec a1) op (exprToSLevel indent (prec+1) a2)
+                        (exprToSLevel indent prec a1), (exprToSLevel indent (prec+1) a2)
+
+                // Add a space to avoid "+" or "-" to be parsed as "++" or "--".
+                let op = if (op = "+" || op = "-") && e2.StartsWith(op) then op + " " else op
+                let res = out "%s%s%s" e1 op e2
                 if prec < level then out "(%s)" res
                 else res
 

tests/unit/operators.expected

@@ -39,6 +39,15 @@
      "x+cos(x):"
      "x*sin(x);"
    "return x*x;"
+ "}"
+ "float cool_ops(float g)"
+ "{"
+   "g=0.;"
+   "g+=g+++ ++g;"
+   "g/=-g+g;"
+   "g-=-g--- --g;"
+   "g*=g+g;"
+   "return--g-++g+g;"
  "}",
 
 #endif

tests/unit/operators.frag

@@ -49,4 +49,15 @@ float desugar_compound_assignment_for_ternary(float x)
 	else
 		x *= sin(x);
 	return x * x;
-}
+}
+
+float cool_ops(float g)
+{
+	float f = 0.0;
+	f += +f++ + ++f;
+	f /= -f - -f;
+	f -= -f-- - --f;
+	f *= +f + +f;
+	f += --f + (- +(++f));
+	return f;
+}

tests/unit/shadowing.frag

@@ -1,5 +1,3 @@
-//NOCOMPILE - https://github.com/laurentlb/shader-minifier/issues/403
-
 float f(float g)
 {
 	float f = 0.0;

tests/unit/shadowing.frag.expected

@@ -1,7 +1,7 @@
 float f(float g)
 {
   g=0.;
-  return g+++++g+g;
+  return g+++ ++g+g;
 }
 float g(float f)
 {