Parse block arguments correctly.

The lexer will eat any whitespace or newlines between the block's
start symbol and the parameter list, if one is present. Otherwise,
the extra NEWLINE tokens will confuse the parser.

Author: smashwilson

examples/input.seg

@@ -1,4 +1,4 @@
 {
-  |a, b|
+  |a, b, c, d|
   3 + 4
 }

src/grammar.y

@@ -122,7 +122,7 @@ expr (OUT) ::= invocation (I). { OUT = I; }
 
 // Blocks
 
-block (OUT) ::= LCURLY parameters (PARAMS) statementlist (BODY) RCURLY.
+block (OUT) ::= BLOCKSTART parameters (PARAMS) statementlist (BODY) BLOCKEND.
 {
   OUT = malloc(sizeof(seg_block_node));
   OUT->parameters = PARAMS;
@@ -136,7 +136,7 @@ commaparams (OUT) ::= parameter (IN). { OUT = IN; }
 commaparams (OUT) ::= commaparams (LIST) COMMA parameter (NEW).
 {
   /* Parameters are pushed in reverse order. */
-  LIST->next = NEW;
+  NEW->next = LIST;
   OUT = NEW;
 }
 

src/lexer.rl

@@ -80,14 +80,17 @@ static void report(const char *name, const char *ts, const char *te) {
 
     '(' => { EMPTY(LPAREN); };
     ')' => { EMPTY(RPAREN); };
-    '{' => { EMPTY(LCURLY); };
-    '}' => { EMPTY(RCURLY); };
     ';' => { EMPTY(SEMI); };
     '\n' => { EMPTY(NEWLINE); };
     '=' => { EMPTY(ASSIGNMENT); };
     '.' => { EMPTY(PERIOD); };
     ',' => { EMPTY(COMMA); };
 
+    # Eat whitespace and newlines at the start of a block.
+    # Otherwise, the extraneous NEWLINE tokens will confuse the parser.
+    '{' (whitespace | [\r\n])* => { EMPTY(BLOCKSTART); };
+    '}' => { EMPTY(BLOCKEND); };
+
     '|' => {
       EMPTY(BAR);
       fcall blockargs;