Feat: added if/else branching and switch statement

Unsure about my modification to the language. I found the parsing of the
case body within switches to be odd - specifically that it parses
liberally and then checks that it has case -> cmd structuring while it
walks the code. This means the language is more permissive than the
semantics. I modified it to be more explicit, but at the cost of having
to end each case statement with a semicolon. I wanted a colon, but this
is a valid word character and thus will be lexed as part of the word.

1 files changed, 18 insertions, 20 deletions

diff --git a/src/cmd/rc/syntax.y b/src/cmd/rc/syntax.y
index 0bdc776..9750002 100644
--- a/src/cmd/rc/syntax.y
+++ b/src/cmd/rc/syntax.y
@@ -65,13 +65,11 @@ ifbody:
 | block Telse nl cmd { $$ = maketree3(Tif, nil, $1, $2); }
 
 case:
-  Tcase words ';'    { $$ = hangchild1($1, $2, 0); }
-| Tcase words '\n'   { $$ = hangchild1($1, $2, 0); }
+  Tcase words ';' nl cmdsln { $$ = hangchild2($1, $2, 0, $5, 1);}
 
 casebody:
-  cmd                { $$ = maketree2(Tcasebody, $1, nil); }
-| case casebody      { $$ = maketree2(Tcasebody, $1, $2); }
-| cmdsln casebody    { $$ = maketree2(Tcasebody, $1, $2); }
+ /* empty */    { $$ = nil; }
+| case casebody { $$ = (!$2) ? $1 : maketree2(';', $1, $2); }
 
 assign:
     executable '=' word { $$ = maketree2('=', $1, $3); }
@@ -85,21 +83,21 @@ epilog:
 | redir epilog  { $$ = hangchild1($1, $2, 1); }
 
 cmd:
-/* empty */  %prec Twhile                  { $$ = nil; }
-| basic                                    { $$ = maketree1(Tbasic, $1); }
-| block epilog                             { $$ = hangepilog($1, $2); }
-| cmd Tpipe nl cmd                         { $$ = hangchild2($2, $1, 0, $4, 1); }
-| cmd Tandand nl cmd                       { $$ = maketree2(Tandand, $1, $4); }
-| cmd Toror nl cmd                         { $$ = maketree2(Toror, $1, $4); }
-| redir  cmd %prec Tbang                   { $$ = hangchild1($1, $2, 1); }
-| assign cmd %prec Tbang                   { $$ = hangchild1($1, $2, 2); }
-| Tbang cmd                                { $$ = maketree1(Tbang, $2); }
-| Tsubshell cmd                            { $$ = maketree1(Tsubshell, $2); }
-| Tfor '(' word ')' nl cmd                 { $$ = hangchild3($1, $3, nil, $6); }
-| Tfor '(' word Tin words ')' nl cmd       { $$ = hangchild3($1, $3, $5, $8); }
-| Twhile paren nl cmd                      { $$ = hangchild2($1, $2, 0, $4, 1); }
-| Tif paren nl ifbody                      { $$ = hangchild1($2, $1, 0); }
-| Tswitch '(' word ')' nl '{' casebody '}' { $$ = hangchild2($1, $3, 0, $7, 1); }
+/* empty */  %prec Twhile                       { $$ = nil; }
+| basic                                         { $$ = maketree1(Tbasic, $1); }
+| block epilog                                  { $$ = hangepilog($1, $2); }
+| cmd Tpipe nl cmd                              { $$ = hangchild2($2, $1, 0, $4, 1); }
+| cmd Tandand nl cmd                            { $$ = maketree2(Tandand, $1, $4); }
+| cmd Toror nl cmd                              { $$ = maketree2(Toror, $1, $4); }
+| redir  cmd %prec Tbang                        { $$ = hangchild1($1, $2, 1); }
+| assign cmd %prec Tbang                        { $$ = hangchild1($1, $2, 2); }
+| Tbang cmd                                     { $$ = maketree1(Tbang, $2); }
+| Tsubshell cmd                                 { $$ = maketree1(Tsubshell, $2); }
+| Tfor '(' word ')' nl cmd                      { $$ = hangchild3($1, $3, nil, $6); }
+| Tfor '(' word Tin words ')' nl cmd            { $$ = hangchild3($1, $3, $5, $8); }
+| Twhile paren nl cmd                           { $$ = hangchild2($1, $2, 0, $4, 1); }
+| Tif paren nl ifbody                           { $$ = hangchild1($2, $2, 0); }
+| Tswitch '(' word ')' nl '{' nl casebody '}'   { $$ = hangchild2($1, $3, 0, $8, 1); }
 
 basic:
   executable