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, 82 insertions, 0 deletions

diff --git a/src/cmd/rc/glob.c b/src/cmd/rc/glob.c
new file mode 100644
index 0000000..9d88b59
--- /dev/null
+++ b/src/cmd/rc/glob.c
@@ -0,0 +1,82 @@
+#include "rc.h"
+
+/* removes glob marks in place */
+void
+deglob(char *s)
+{
+    char *t = s;
+    do{
+        if(*t==GLOB)
+            t++;
+        *s++=*t;
+    }while(*t++);
+}
+
+int
+match(char *s, char *p,  int stop)
+{
+    rune rs, rp, lo, hi;
+    int neg, hit;
+
+    utf8·decode(p, &rp), utf8·decode(s, &rs);
+    for(; *p && *p != stop; s+=utf8·decode(s,&rs),p+=utf8·decode(p,&rp)){
+        /* fast path: normal character */
+        if(*p != GLOB){
+            if(rp != rs)
+                return 0;
+            continue;
+        }
+
+        /* unglob */
+        switch(*++p){
+        case GLOB:
+            if(*s != GLOB)
+                return 0;
+            break;
+        case '*':
+            for(;;){
+                p += utf8·decode(p, &rp);
+                if(match(s, p, stop))
+                    return 1;
+                s += utf8·decode(s, &rs);
+            }
+            return 0;
+
+        case '?':
+            if(*s == 0)
+                return 0;
+            break;
+
+        case '[':
+            if(*s==0)
+                return 0;
+            if((neg=*++p=='~'))
+                p++;
+            hit = 0;
+            while(*p != ']'){
+                if(*p==0)
+                    return 0; /* syntax error */
+                p += utf8·decode(p, &lo);
+                if(*p != '-')
+                   hi = lo;
+                else{
+                    if(*++p == 0)
+                        return 0; /* syntax error */
+                    p += utf8·decode(p, &hi);
+                    if(hi < lo)
+                        rp=lo, lo=hi, hi=rp;
+                }
+
+                if(lo <= rs && rs <= hi)
+                    hit = 1;
+            }
+            if(neg)
+                hit=!hit;
+            if(!hit)
+                return 0;
+            break;
+        }
+    }
+
+    return *s == 0;
+}