Parse in terms of lines and slash separators

The grammar rules for LF and `/` are inconsistent:

* The first instruction can have slashes before it and the last line can
  end with a slash.
* Multiple slashes are treated as a single slash. Spaces or comments
  cannot be between slashes, except at the start of the file or after a
  label definition.
* Lines containing only whitespace or comments are not allowed, except
  at the start of the file or after label definitions.
* The last line must be terminated with LF.

Simplify the rules to be line-based:

* A line cannot start or end with a slash.
* A single slash separates adjacent instructions on the same line, but
  is optional after a label definition.

asm.l

@@ -76,8 +76,8 @@
 -?[01]+[bB]                 { yylval->string = strdup(yytext); return NUMBER; }
 -?[0-9][0-9A-Fa-f]*[hH]     { yylval->string = strdup(yytext); return NUMBER; }
 -?[0-9]+                    { yylval->string = strdup(yytext); return NUMBER; }
-\n+                         { return LF; }
-"/"+                        { return LF; }
+\n                          { return LF; }
+"/"                         { return SLASH; }
 [\t\r\f ]                   { ; }
 .                           { fprintf(stderr, "wsi: unrecognized token at line %d: `%c'", yylineno, *yytext); }
 

asm.y

@@ -17,6 +17,8 @@
 
     #define node(type, param) (struct node_t) { type, param, imm_none(), imm_none(), yyloc.first_line, yyloc.first_column }
     #define node2(type, param1, param2) (struct node_t) { type, param1, param2, imm_none(), yyloc.first_line, yyloc.first_column }
+
+    vector(struct node_t) insn = NULL;
 }
 
 %code requires {
@@ -26,7 +28,6 @@
 %union {
     char * string;
     struct node_t ins;
-    vector(struct node_t) insn;
     struct immediate_t imm;
 }
 
@@ -37,33 +38,47 @@
 
 %token END 0 "end of file"
 
-%type<insn> ToplevelScope
 %type<ins> Construct
 %type<imm> NumericalConstant
 %token I_GETC I_GETN I_PUTC I_PUTN
 %token I_PSH I_DUP I_XCHG I_DROP I_COPY I_SLIDE
 %token I_ADD I_SUB I_MUL I_DIV I_MOD
 %token I_STO I_RCL
 %token I_CALL I_JMP I_JZ I_JLTZ I_RET I_END
-%token I_REP COMMA LF
+%token I_REP COMMA SLASH LF
 
 %token<string> CHAR STRING NUMBER G_LBL G_REF
 
 %start Start
 %%
 Start
-: MaybeLF ToplevelScope { asm_gen(stdout, $2, optlevel); }
+: Lines Line { asm_gen(stdout, insn, optlevel); }
+;
+
+Lines
+: Lines Line LF
+| %empty
+;
+
+Line
+: Instructions LastInstruction
+| %empty
+;
+
+Instructions
+: Instructions G_LBL OptionalSLASH { vector_push_back(insn, node(LBL, imm_lbl($2))); }
+| Instructions Construct SLASH { vector_push_back(insn, $2); }
+| %empty
 ;
 
-MaybeLF
-: %empty
-| LF MaybeLF
+LastInstruction
+: G_LBL { vector_push_back(insn, node(LBL, imm_lbl($1))); }
+| Construct { vector_push_back(insn, $1); }
 ;
 
-ToplevelScope
-: ToplevelScope Construct LF { vector_push_back($1, $2); $$ = $1; }
-| ToplevelScope G_LBL MaybeLF { vector_push_back($1, node(LBL, imm_lbl($2))); $$ = $1; }
-| %empty { $$ = NULL; }
+OptionalSLASH
+: SLASH
+| %empty
 ;
 
 Construct

tests/parsing/fail/slash/inst_slash_space_slash.asm

@@ -0,0 +1 @@
+push 1 / / push 2

tests/parsing/fail/slash/label_slash_space_slash.asm

@@ -0,0 +1 @@
+@lbl / / push 1

tests/parsing/fail/slash/lf_slash.asm

@@ -0,0 +1,2 @@
+push 1
+/ push 2

tests/parsing/fail/slash/slash_eof.asm

@@ -0,0 +1 @@
+push 1 /

tests/parsing/fail/slash/slash_lf.asm

@@ -0,0 +1,2 @@
+push 1 /
+push 2

tests/parsing/fail/slash/slash_lf_eof.asm

@@ -0,0 +1 @@
+push 1 /

tests/parsing/fail/slash/slash_slash.asm

@@ -0,0 +1 @@
+push 1 // push 2

tests/parsing/fail/slash/sof_slash.asm

@@ -0,0 +1 @@
+/ push 1

tests/parsing/regress/pass/no_final_lf.asm

@@ -0,0 +1 @@
+push 1

tests/parsing/regress/pass/no_final_lf.ws

@@ -0,0 +1 @@
+