Chapter 22: A Hello, World!

Co-authored-by: godalming123 <68993177+godalming123@users.noreply.github.com>
Co-authored-by: Tamás Hadházy <85063808+Hels15@users.noreply.github.com>
Co-authored-by: Hsiang-Ying Fu <66062782+fuhsnn@users.noreply.github.com>

2 files changed, 112 insertions, 0 deletions

diff --git a/docs/chapter22/examples/A_helloWorld.smp b/docs/chapter22/examples/A_helloWorld.smp
new file mode 100644
index 00000000..07ff935f
--- /dev/null
+++ b/docs/chapter22/examples/A_helloWorld.smp
@@ -0,0 +1,3 @@
+// -*- mode: java;  -*-
+sys.io.p("Hello, World!");
+return 0;
diff --git a/docs/chapter22/examples/BubbleSort.smp b/docs/chapter22/examples/BubbleSort.smp
new file mode 100644
index 00000000..aa9cbbb8
--- /dev/null
+++ b/docs/chapter22/examples/BubbleSort.smp
@@ -0,0 +1,109 @@
+// -*- mode: java;  -*-
+
+// An implementation of
+// https://sampleprograms.io/projects/bubble-sort/
+//
+// Bubble sort, with reading (parsing) and writing (formatting) the data.
+
+
+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] <= ' ' )
+        s.x++;
+};
+
+
+// Require specific syntax or usage
+val require = { Scan s, u8 c ->
+    skip(s);
+    if( s.buf[s.x++] != c )
+        usage();
+};
+
+val peek = { Scan s, u8 c ->
+    skip(s);
+    if( s.buf[s.x] != c ) return false;
+    s.x++;
+    return true;
+};
+
+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;
+};
+
+val sort = { int[] ns, int len ->
+    var done = false;
+    while( !done ) {
+        done = true;
+        for( var i = 0; i < len-1; i++ )
+            if( ns[i] > ns[i+1] ) {
+                int tmp = ns[i];
+                ns[i] = ns[i+1];
+                ns[i+1] = tmp; // Swap
+                done = false;
+            }
+    }
+};
+
+// 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(); };
+    require(s,'[');
+    // Array of parsed results
+    int[] !ns = new int[16];
+    i32 len = 0;
+    // Parse a list of numbers
+    if( !peek(s,']') ) {        // Handle the empty list
+        // Parse "123, " until a something else
+        while( s.x < s.buf# ) {
+            int n = number(s);
+            ns[len++] = n;
+            if( !peek(s,',') )
+                break;
+        };
+        require(s,']');         // Close the list
+    }
+
+    // Bubble sort array of integers
+    sort(ns,len);
+
+    // Print a list of numbers
+    sys.io.p("[ ");
+    u8[] !junk = new u8[1];
+    for( int i=0; i<len; i++ ) {
+        int x = ns[i];
+        if( !x ) { sys.io.p("0, "); continue; }
+
+        int ten = 1, log = 0;
+        while( ten <= x ) { ten *= 10; log++; }
+        ten /= 10;
+        for( int i=0; i<log; i++ ) {
+            int q = x/ten;
+            int r = x - q*ten;
+            junk[0] = q+'0';
+            sys.io.p(junk);
+            x = r;
+            ten /= 10;
+        }
+        sys.io.p(", ");
+    }
+    sys.io.p("]");
+    return 0;
+};