Remove unnecessary parentheses between ? and : in ternary expressions (…

…#396)

The rules for how `? :` parse:
- everything between `?` and `:` is parsed as if grouped (just like `(
)` and `{ }`), so the parens can always be omitted from the middle
expression.
- The entire `? expr :` is parsed as if it is one whole binary operator
in relation to the expressions on either side of it, according to normal
precedence rules, thus `?:` gets its spot in the precedence table in the
spec despite its more complex grammar.

src/printer.fs

@@ -117,7 +117,8 @@ type PrinterImpl(withLocations) =
             | Op "?:", [a1; a2; a3] ->
                 let prec = precedence.["?:"]
                 let res = out "%s?%s%s:%s%s" (exprToSLevel indent (prec+1) a1)
-                            (nl (indent+1)) (exprToSLevel (indent+1) prec a2)
+                    // The middle expression of ?: is parsed as if grouped: precedence doesn't apply to it.
+                            (nl (indent+1)) (exprToSLevel (indent+1) 0 a2)
                             (nl (indent+1)) (exprToSLevel (indent+1) prec a3)
                 if prec < level then out "(%s)" res else res
 

tests/real/controllable-machinery.frag.expected

@@ -28,13 +28,13 @@ vec4 BPos(float t)
   float a;
   t=mod(t,tCyc);
   p=t<5.?
-    (a=0.,vec3(-1.018+2.118*t/5.,bEdge,0)):
+    a=0.,vec3(-1.018+2.118*t/5.,bEdge,0):
     t<10.?
-      (a=1.57079635*(t-5.)/5.,vec3(1.1,bEdge+sin(a),1.-cos(a))):
+      a=1.57079635*(t-5.)/5.,vec3(1.1,bEdge+sin(a),1.-cos(a)):
       t<15.?
-        (a=1.57079635,vec3(1.1-2.118*(t-10.)/5.,1.+bEdge,1)):
+        a=1.57079635,vec3(1.1-2.118*(t-10.)/5.,1.+bEdge,1):
         t<17.5?
-          (a=1.57079635,vec3(-1.018,1.+bEdge,1.-(t-15.)/2.5)):
+          a=1.57079635,vec3(-1.018,1.+bEdge,1.-(t-15.)/2.5):
           (t-=17.5,a=-1.57079635*t,vec3(-1.018,1.+bEdge-t*t,0));
   return vec4(p,a);
 }
@@ -355,7 +355,7 @@ vec3 ShowScene(vec3 ro,vec3 rd)
   idObjT=idObj;
   dstGear=GearRay(ro,rd);
   idObj=dstGear<min(dstObj,dstFar)?
-    (dstObj=dstGear,1):
+    dstObj=dstGear,1:
     idObjT;
   dstBlk=BlkHit(ro,rd);
   if(min(dstBlk,dstObj)<dstFar)

tests/real/frozen-wasteland.frag.expected

@@ -235,7 +235,7 @@ void mainImage(out vec4 fragColor,vec2 fragCoord)
   p.x*=iResolution.x/iResolution.y;
   vec2 mo=iMouse.xy/iResolution.xy-.5;
   mo=mo==vec2(-.5)?
-    (mo=vec2(-.1,.07)):
+    mo=vec2(-.1,.07):
     mo;
   mo.x*=iResolution.x/iResolution.y;
   vec3 ro=vec3(smoothstep(0.,1.,tri(time*1.5)*.3)*1.5,smoothstep(0.,1.,tri(time*3.)*3.)*.08,-time*3.5-130.);

tests/real/kinder_painter.expected

@@ -63,9 +63,9 @@
  "{"
    "vec3 z;"
    "b=m.w>2.5?"
-     "(z.xz=r.xz-v.xz,z.y=0.,z/=v.w,vec2(z.x,r.y)):"
+     "z.xz=r.xz-v.xz,z.y=0.,z/=v.w,vec2(z.x,r.y):"
      "m.w>1.5?"
-       "(z=v.xyz,r.xz*.2):"
+       "z=v.xyz,r.xz*.2:"
        "(z=(r-v.xyz)/v.w,z.xy);"
    "return z;"
  "}"

tests/real/mouton/mouton.expected

@@ -200,7 +200,7 @@ const char *mouton_vert =
        "f=vec3(0);"
        "x=vec3(0,0,-8);"
        "e=mod(v,3.)<1.5?"
-         "(d=0.,c=vec3(0,2,-8),vec3(0,3,0)):"
+         "d=0.,c=vec3(0,2,-8),vec3(0,3,0):"
          "(c=vec3(0,5.5,2),vec3(0,5.75,0));"
        "l=vec3(0,-.1,1);"
        "o=3.+v*.1;"
@@ -361,7 +361,7 @@ const char *mouton_frag =
    "v.y-=-z.y;"
    "float y=v.y+smoothstep(1.,20.,length(v.xz));"
    "return y<.4?"
-     "(y-=pow((B(v*.9)*.5+B(v*1.6)*.3+B(v*2.7)*.1)*.5+.5,3.)*.45*(1.-exp((-t+137.3)*3.)),vec2(y,12)):"
+     "y-=pow((B(v*.9)*.5+B(v*1.6)*.3+B(v*2.7)*.1)*.5+.5,3.)*.45*(1.-exp((-t+137.3)*3.)),vec2(y,12):"
      "vec2(9e7,0);"
  "}"
  "mat3 A(vec3 v,vec3 y)"

tests/unit/ternary.frag.expected

@@ -15,7 +15,7 @@ void main()
 {
   int d=0,e=0;
   k==0?
-    (sin(O.x),d=1):
+    sin(O.x),d=1:
     (cos(O.x),e=2);
   O.x=float(d);
   O.y=float(e);
@@ -25,3 +25,4 @@ int f2()
   k++;
   return k;
 }
+