Don't treat negative numbers as literals

Fixes #93.

Previously, "1 -1" was lexed as two number tokens: a positive literal and
a negative literal. This caused problems when it came to parsing.

Now the '-' and the second number are separate tokens.

Note this is a breaking change, since `-16.sqrt` is now parsed as `-(16.sqrt)`,
as opposed to `(-16).sqrt`.

There is a small bit of overhead to doing it this way, but it might be possible
to optimize that out in the compiler at some point in the future.

src/wren_compiler.c

@@ -752,14 +752,7 @@ static void nextToken(Parser* parser)
         return;
 
       case '-':
-        if (isDigit(peekChar(parser)))
-        {
-          readNumber(parser);
-        }
-        else
-        {
-          makeToken(parser, TOKEN_MINUS);
-        }
+        makeToken(parser, TOKEN_MINUS);
         return;
 
       case '|':

test/grammar.wren

@@ -25,6 +25,12 @@ IO.print(false == 1 >= 2) // expect: true
 // Unary - has lower precedence than ..
 IO.print(-"abc".count) // expect: -3
 
+// 1 - 1 is not space-sensitive.
+IO.print(1 - 1) // expect: 0
+IO.print(1 -1)  // expect: 0
+IO.print(1- 1)  // expect: 0
+IO.print(1-1)   // expect: 0
+
 // TODO: %, associativity.
 
 // Using () for grouping.

test/number/abs.wren

@@ -1,6 +1,6 @@
-IO.print(123.abs)    // expect: 123
-IO.print(-123.abs)   // expect: 123
-IO.print(0.abs)      // expect: 0
-IO.print(-0.abs)     // expect: 0
-IO.print(-0.12.abs)  // expect: 0.12
-IO.print(12.34.abs)  // expect: 12.34
+IO.print(123.abs)      // expect: 123
+IO.print((-123).abs)   // expect: 123
+IO.print(0.abs)        // expect: 0
+IO.print((-0).abs)     // expect: 0
+IO.print((-0.12).abs)  // expect: 0.12
+IO.print(12.34.abs)    // expect: 12.34

test/number/ceil.wren

@@ -1,8 +1,8 @@
-IO.print(123.ceil)    // expect: 123
-IO.print(-123.ceil)   // expect: -123
-IO.print(0.ceil)      // expect: 0
-IO.print(-0.ceil)     // expect: -0
-IO.print(0.123.ceil)  // expect: 1
-IO.print(12.3.ceil)   // expect: 13
-IO.print(-0.123.ceil) // expect: -0
-IO.print(-12.3.ceil)  // expect: -12
+IO.print(123.ceil)      // expect: 123
+IO.print((-123).ceil)   // expect: -123
+IO.print(0.ceil)        // expect: 0
+IO.print((-0).ceil)     // expect: -0
+IO.print(0.123.ceil)    // expect: 1
+IO.print(12.3.ceil)     // expect: 13
+IO.print((-0.123).ceil) // expect: -0
+IO.print((-12.3).ceil)  // expect: -12

test/number/floor.wren

@@ -1,8 +1,8 @@
-IO.print(123.floor)    // expect: 123
-IO.print(-123.floor)   // expect: -123
-IO.print(0.floor)      // expect: 0
-IO.print(-0.floor)     // expect: -0
-IO.print(0.123.floor)  // expect: 0
-IO.print(12.3.floor)   // expect: 12
-IO.print(-0.123.floor) // expect: -1
-IO.print(-12.3.floor)  // expect: -13
+IO.print(123.floor)      // expect: 123
+IO.print((-123).floor)   // expect: -123
+IO.print(0.floor)        // expect: 0
+IO.print((-0).floor)     // expect: -0
+IO.print(0.123.floor)    // expect: 0
+IO.print(12.3.floor)     // expect: 12
+IO.print((-0.123).floor) // expect: -1
+IO.print((-12.3).floor)  // expect: -13

test/number/sqrt.wren

@@ -1,10 +1,10 @@
 IO.print(4.sqrt)        // expect: 2
 IO.print(1000000.sqrt)  // expect: 1000
 IO.print(1.sqrt)        // expect: 1
-IO.print(-0.sqrt)       // expect: -0
+IO.print((-0).sqrt)     // expect: -0
 IO.print(0.sqrt)        // expect: 0
 IO.print(2.sqrt)        // expect: 1.4142135623731
 
-IO.print(-4.sqrt.isNan) // expect: true
+IO.print((-4).sqrt.isNan) // expect: true
 
 // TODO: Tests for sin and cos.

test/number/to_string.wren

@@ -1,5 +1,5 @@
 IO.print(123.toString == "123") // expect: true
-IO.print(-123.toString == "-123") // expect: true
-IO.print(-0.toString == "-0") // expect: true
+IO.print((-123).toString == "-123") // expect: true
+IO.print((-0).toString == "-0") // expect: true
 IO.print(12.34.toString == "12.34") // expect: true
-IO.print(-0.0001.toString == "-0.0001") // expect: true
+IO.print((-0.0001).toString == "-0.0001") // expect: true