1 files changed, 26 insertions, 5 deletions
diff --git a/chapter22/docs/examples/BubbleSort.smp b/chapter22/docs/examples/BubbleSort.smp
index af110159..025bb5a2 100644
--- a/chapter22/docs/examples/BubbleSort.smp
+++ b/chapter22/docs/examples/BubbleSort.smp
@@ -1,25 +1,46 @@
 // -*- mode: java;  -*-
 
-
 val _exit = { u8[~] msg ->
     sys.io.p(msg);
     sys.libc._exit(1);
 };
+val usage = { -> _exit("stdin must look like [4, 3, 2, 1]"); };
 
+// Scanner
 struct Scan {
     int !x;
     u8[~] buf;
 };
 
+// Skip whitespace
+val skip = { Scan s ->
+    while( s.buf[s.x] <= 32 )
+        s.x++;
+};
+
+// Require specific syntax or usage
+val require = { Scan s, u8 c ->
+    skip(s);
+    if( s.buf[s.x++] != c )
+        usage();
+};
+
+val number = { Scan s ->
+    skip(s);
+    i32 n = 0;
+    while( '0' <= s.buf[s.x] & s.buf[s.x] <= '9' )
+        n = n*10 + (s.buf[s.x++] - '0');
+    return n;
+};
+
 
 // Read from stdin a line of the form "[ 4, 3, 2, 1]" and print it sorted.
 val main = { ->
     Scan !s = new Scan{ buf = sys.io.stdin(); };
-    var junk = new u8[1];
     while( s.x < s.buf# ) {
-        sys.io.p("scan ");
-        junk[0] = s.buf[s.x++];
-        sys.io.p(junk);
+        require(s,'[');
+        int n = number(s);
+        sys.libc._exit(n);
     };
     return 0;
 };