make/jdk/src/classes/build/tools/hasher/Hasher.java
changeset 47216 71c04702a3d5
parent 23010 6dadb192ad81
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/make/jdk/src/classes/build/tools/hasher/Hasher.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,320 @@
+/*
+ * Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package build.tools.hasher;
+
+import java.io.*;
+import java.util.*;
+
+
+/**
+ * Reads a map in the form of a sequence of key/value-expression pairs from the
+ * standard input, attempts to construct a hash map that fits within the given
+ * table-size and chain-depth constraints, and, if successful, writes source
+ * code to the standard output for a subclass of sun.util.PreHashedMap that
+ * implements the map.
+ *
+ * @see sun.util.PreHashedMap
+ *
+ * @author Mark Reinhold
+ */
+
+public class Hasher {
+
+    static final PrintStream out = System.out;
+    static final PrintStream err = System.err;
+
+    boolean verbose = false;
+
+    List<String> keys = new ArrayList<>();      // Key strings
+    List<String> values = new ArrayList<>();    // Value expressions
+    String pkg = null;                          // Package prefix for generated class
+    String cln = null;                          // Name of generated class
+    String vtype = "String";                    // Value type
+    int maxBits = 11;                           // lg table size
+    int maxDepth = 3;                           // Max chain depth
+    boolean inner = false;                      // Generating an inner class?
+    boolean empty = false;                      // Generating an empty table?
+
+    void usage() {
+        err.println("usage: java Hasher [options] [[pkgName.]ClassName]");
+        err.println("options:");
+        err.println("    -e           generate empty table (ignores value exprs)");
+        err.println("    -i           generate a static inner class");
+        err.println("    -md depth    max chain depth (default 3)");
+        err.println("    -mb bits     max index bits (lg of table size, default 10)");
+        err.println("    -t type      value type (default String)");
+        err.println("    -v           verbose");
+        err.println("Key/value-expression pairs are read from standard input");
+        err.println("If class name is given then source is written to standard output");
+        System.exit(1);
+    }
+
+    Hasher(String[] args) {
+        List<String> as = Arrays.asList(args);
+        for (Iterator<String> i = as.iterator(); i.hasNext();) {
+            String a = i.next();
+            if (a.equals("-e")) {
+                empty = true;
+            } else if (a.equals("-i")) {
+                inner = true;
+            } else if (a.equals("-v")) {
+                verbose = true;
+            } else if (a.equals("-md")) {
+                if (!i.hasNext())
+                    usage();
+                maxDepth = Integer.parseInt(i.next());
+            } else if (a.equals("-mb")) {
+                if (!i.hasNext())
+                    usage();
+                maxBits = Integer.parseInt(i.next());
+            } else if (a.equals("-t")) {
+                if (!i.hasNext())
+                    usage();
+                vtype = i.next();
+            } else if (a.startsWith("-")) {
+                usage();
+            } else {
+                int j = a.lastIndexOf('.');
+                if (j >= 0) {
+                    pkg = a.substring(0, j);
+                    cln = a.substring(j + 1);
+                } else {
+                    cln = a;
+                }
+            }
+        }
+        if (verbose)
+            err.println("pkg=" + pkg + ", cln=" + cln);
+    }
+
+    // Read keys and values
+    //
+    Hasher load() throws IOException {
+        BufferedReader br
+            = new BufferedReader(new InputStreamReader(System.in));
+        for (String ln; (ln = br.readLine()) != null;) {
+            String[] ws = ln.split(",?\\s+", 2);
+            String w = ws[0].replaceAll("\"", "");
+            if (keys.contains(w))
+                throw new RuntimeException("Duplicate word in input: " + w);
+            keys.add(w);
+            if (ws.length < 2)
+                throw new RuntimeException("Missing expression for key " + w);
+            values.add(ws[1]);
+        }
+        return this;
+    }
+
+    Object[] ht;                        // Hash table itself
+    int nb;                             // Number of bits (lg table size)
+    int md;                             // Maximum chain depth
+    int mask;                           // Hash-code mask
+    int shift;                          // Hash-code shift size
+
+    int hash(String w) {
+        return (w.hashCode() >> shift) & mask;
+    }
+
+    // Build a hash table of size 2^nb, shifting the hash code by s bits
+    //
+    void build(int nb, int s) {
+
+        this.nb = nb;
+        this.shift = s;
+        int n = 1 << nb;
+        this.mask = n - 1;
+        ht = new Object[n];
+        int nw = keys.size();
+
+        for (int i = 0; i < nw; i++) {
+            String w = keys.get(i);
+            String v = values.get(i);
+            int h = hash(w);
+            if (ht[h] == null)
+                ht[h] = new Object[] { w, v };
+            else
+                ht[h] = new Object[] { w, v, ht[h] };
+        }
+
+        this.md = 0;
+        for (int i = 0; i < n; i++) {
+            int d = 1;
+            for (Object[] a = (Object[])ht[i];
+                 a != null && a.length > 2;
+                 a = (Object[])a[2], d++);
+            this.md = Math.max(md, d);
+        }
+
+    }
+
+    Hasher build() {
+        // Iterate through acceptable table sizes
+        for (int nb = 2; nb < maxBits; nb++) {
+            // Iterate through possible shift sizes
+            for (int s = 0; s < (32 - nb); s++) {
+                build(nb, s);
+                if (verbose)
+                    err.println("nb=" + nb + " s=" + s + " md=" + md);
+                if (md <= maxDepth) {
+                    // Success
+                    out.flush();
+                    if (verbose) {
+                        if (cln != null)
+                            err.print(cln + ": ");
+                        err.println("Table size " + (1 << nb) + " (" + nb + " bits)"
+                                    + ", shift " + shift
+                                    + ", max chain depth " + md);
+                    }
+                    return this;
+                }
+            }
+        }
+        throw new RuntimeException("Cannot find a suitable size"
+                                   + " within given constraints");
+    }
+
+    // Look for the given key in the hash table
+    //
+    String get(String k) {
+        int h = hash(k);
+        Object[] a = (Object[])ht[h];
+        for (;;) {
+            if (a[0].equals(k))
+                return (String)a[1];
+            if (a.length < 3)
+                return null;
+            a = (Object[])a[2];
+        }
+    }
+
+    // Test that all input keys can be found in the table
+    //
+    Hasher test() {
+        if (verbose)
+            err.println();
+        for (int i = 0, n = keys.size(); i < n; i++) {
+            String w = keys.get(i);
+            String v = get(w);
+            if (verbose)
+                err.println(hash(w) + "\t" + w);
+            if (!v.equals(values.get(i)))
+                throw new Error("Incorrect value: " + w + " --> "
+                                + v + ", should be " + values.get(i));
+        }
+        return this;
+    }
+
+    String ind = "";                    // Indent prefix
+
+    // Generate code for a single table entry
+    //
+    void genEntry(Object[] a, int depth, PrintWriter pw) {
+        Object v = empty ? null : a[1];
+        pw.print("new Object[] { \"" + a[0] + "\", " + v);
+        if (a.length < 3) {
+            pw.print(" }");
+            return;
+        }
+        pw.println(",");
+        pw.print(ind + "                     ");
+        for (int i = 0; i < depth; i++)
+            pw.print("    ");
+        genEntry((Object[])a[2], depth + 1, pw);
+        pw.print(" }");
+    }
+
+    // Generate a PreHashedMap subclass from the computed hash table
+    //
+    Hasher generate() throws IOException {
+        if (cln == null)
+            return this;
+        PrintWriter pw
+            = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out)));
+
+        if (inner)
+            ind = "    ";
+
+        if (!inner && pkg != null) {
+            pw.println();
+            pw.println("package " + pkg + ";");
+            pw.println();
+        }
+
+        if (inner) {
+            pw.println(ind + "private static final class " + cln);
+        } else {
+            pw.println();
+            pw.println("public final class " + cln);
+        }
+        pw.println(ind + "    extends sun.util.PreHashedMap<" + vtype +">");
+        pw.println(ind + "{");
+
+        pw.println();
+        pw.println(ind + "    private static final int ROWS = "
+                   + ht.length + ";");
+        pw.println(ind + "    private static final int SIZE = "
+                   + keys.size() + ";");
+        pw.println(ind + "    private static final int SHIFT = "
+                   + shift + ";");
+        pw.println(ind + "    private static final int MASK = 0x"
+                   + Integer.toHexString(mask) + ";");
+        pw.println();
+
+        pw.println(ind + "    " + (inner ? "private " : "public ")
+                   + cln + "() {");
+        pw.println(ind + "        super(ROWS, SIZE, SHIFT, MASK);");
+        pw.println(ind + "    }");
+        pw.println();
+
+        pw.println(ind + "    protected void init(Object[] ht) {");
+        for (int i = 0; i < ht.length; i++) {
+            if (ht[i] == null)
+                continue;
+            Object[] a = (Object[])ht[i];
+            pw.print(ind + "        ht[" + i + "] = ");
+            genEntry(a, 0, pw);
+            pw.println(";");
+        }
+        pw.println(ind + "    }");
+        pw.println();
+
+        pw.println(ind + "}");
+        if (inner)
+            pw.println();
+
+        pw.close();
+        return this;
+    }
+
+    public static void main(String[] args) throws IOException {
+        new Hasher(args)
+            .load()
+            .build()
+            .test()
+            .generate();
+    }
+
+}