whatcanGOwrong

go/pkg/mod/golang.org/x/exp@v0.0.0-20230224173230-c95f2b4c22f2/shootout/chameneosredux.go

@@ -0,0 +1,183 @@
+//go:build ignore
+// +build ignore
+
+/*
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+
+    * Neither the name of "The Computer Language Benchmarks Game" nor the
+    name of "The Computer Language Shootout Benchmarks" nor the names of
+    its contributors may be used to endorse or promote products derived
+    from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/* The Computer Language Benchmarks Game
+ * http://shootout.alioth.debian.org/
+ *
+ * contributed by The Go Authors.
+ */
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strconv"
+)
+
+const (
+	blue = iota
+	red
+	yellow
+	ncol
+)
+
+var complement = [...]int{
+	red | red<<2:       red,
+	red | yellow<<2:    blue,
+	red | blue<<2:      yellow,
+	yellow | red<<2:    blue,
+	yellow | yellow<<2: yellow,
+	yellow | blue<<2:   red,
+	blue | red<<2:      yellow,
+	blue | yellow<<2:   red,
+	blue | blue<<2:     blue,
+}
+
+var colname = [...]string{
+	blue:   "blue",
+	red:    "red",
+	yellow: "yellow",
+}
+
+// information about the current state of a creature.
+type info struct {
+	colour int // creature's current colour.
+	name   int // creature's name.
+}
+
+// exclusive access data-structure kept inside meetingplace.
+// if mate is nil, it indicates there's no creature currently waiting;
+// otherwise the creature's info is stored in info, and
+// it is waiting to receive its mate's information on the mate channel.
+type rendez struct {
+	n    int         // current number of encounters.
+	mate chan<- info // creature waiting when non-nil.
+	info info        // info about creature waiting.
+}
+
+// result sent by each creature at the end of processing.
+type result struct {
+	met  int
+	same int
+}
+
+var n = 600
+
+func main() {
+	flag.Parse()
+	if flag.NArg() > 0 {
+		n, _ = strconv.Atoi(flag.Arg(0))
+	}
+
+	for c0 := 0; c0 < ncol; c0++ {
+		for c1 := 0; c1 < ncol; c1++ {
+			fmt.Printf("%s + %s -> %s\n", colname[c0], colname[c1], colname[complement[c0|c1<<2]])
+		}
+	}
+	fmt.Print("\n")
+
+	pallmall([]int{blue, red, yellow})
+	pallmall([]int{blue, red, yellow, red, yellow, blue, red, yellow, red, blue})
+}
+
+func pallmall(cols []int) {
+
+	// invariant: meetingplace always contains a value unless a creature
+	// is currently dealing with it (whereupon it must put it back).
+	meetingplace := make(chan rendez, 1)
+	meetingplace <- rendez{n: 0}
+
+	ended := make(chan result)
+	msg := ""
+	for i, col := range cols {
+		go creature(info{col, i}, meetingplace, ended)
+		msg += " " + colname[col]
+	}
+	fmt.Println(msg)
+	tot := 0
+	// wait for all results
+	for range cols {
+		result := <-ended
+		tot += result.met
+		fmt.Printf("%v%v\n", result.met, spell(result.same, true))
+	}
+	fmt.Printf("%v\n\n", spell(tot, true))
+}
+
+// in this function, variables ending in 0 refer to the local creature,
+// variables ending in 1 to the creature we've met.
+func creature(info0 info, meetingplace chan rendez, ended chan result) {
+	c0 := make(chan info)
+	met := 0
+	same := 0
+	for {
+		var othername int
+		// get access to rendez data and decide what to do.
+		switch r := <-meetingplace; {
+		case r.n >= n:
+			// if no more meetings left, then send our result data and exit.
+			meetingplace <- rendez{n: r.n}
+			ended <- result{met, same}
+			return
+		case r.mate == nil:
+			// no creature waiting; wait for someone to meet us,
+			// get their info and send our info in reply.
+			meetingplace <- rendez{n: r.n, info: info0, mate: c0}
+			info1 := <-c0
+			othername = info1.name
+			info0.colour = complement[info0.colour|info1.colour<<2]
+		default:
+			// another creature is waiting for us with its info;
+			// increment meeting count,
+			// send them our info in reply.
+			r.n++
+			meetingplace <- rendez{n: r.n, mate: nil}
+			r.mate <- info0
+			othername = r.info.name
+			info0.colour = complement[info0.colour|r.info.colour<<2]
+		}
+		if othername == info0.name {
+			same++
+		}
+		met++
+	}
+}
+
+var digits = [...]string{"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"}
+
+func spell(n int, required bool) string {
+	if n == 0 && !required {
+		return ""
+	}
+	return spell(n/10, false) + " " + digits[n%10]
+}