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    FAUST compiler
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    ---------------------------------------------------------------------
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 ************************************************************************
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/*****************************************************************************
******************************************************************************
                          Tree Sharing Analysis
                        Y. Orlarey, (c) Grame 2002
------------------------------------------------------------------------------
The sharing analysis of tree t is the annotation of all its subtrees t'
with their number of occurences in t. As this annotation of t' depends of
a context (the tree t for which t' is a subtree) a specific property key
unique to each sharing analysis must be generated.

 API:
 ----

    shprkey(t) -> k     = unique sharing property key of t
    shcount(k,t') -> n  = returns the number of occurences of t' in t (where k = shprkey(t))
    shlysis(t)    -> k  = annotated the subtrees of t with prop (key sharing-count)
                          (0 if t' is not a subtree of t)

 History :
 ---------
    2002-04-08 : First version
    2006-03-25 : Modifications for new symbolic rec trees

******************************************************************************
*****************************************************************************/

/**
 * @file shlysis.cpp
 * The sharing analysis of tree t is the annotation of all its subtrees t'
 * with their number of occurences in t. As this annotation of t' depends of
 * a context (the tree t for which t' is a subtree) a specific property key
 * unique to each sharing analysis must be generated.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "compatibility.hh"
#include "shlysis.hh"

/**
 * Create a specific property key for the sharing count of subtrees of t
 */

Tree shprkey(Tree t)
{
    char name[256];
    snprintf(name, 256, "SHARED IN %p : ", t);
    return tree(unique(name));
}

/**
 * Return the value of sharing count or 0
 */

int shcount(Tree key, Tree t)
{
    Tree c;
    if (getProperty(t, key, c)) {
        return c->node().getInt();
    } else {
        return 0;
    }
}

//------------------------------------------------------------------------------
// Create a specific property key for the sharing count of subtrees of t
//------------------------------------------------------------------------------

static void annotate(Tree k, Tree t, barrier foo);

static bool nobarrier(const Tree& t)
{
    return false;
}

/**
 * Do a sharing analysis : annotates all the subtrees of t
 * with there occurences
 */
Tree shlysis(Tree t, barrier foo)
{
    Tree k = shprkey(t);
    annotate(k, t, foo);
    return k;
}

/**
 * Do a sharing analysis : annotates all the subtrees of t
 * with there occurences
 */
Tree shlysis(Tree t)
{
    Tree k = shprkey(t);
    annotate(k, t, nobarrier);
    return k;
}

/**
 * Recursively increment the occurences count
 * of t and its subtrees
 */
static void annotate(Tree k, Tree t, barrier foo)
{
    // cerr << "Annotate " << *t << endl;
    int c = shcount(k, t);
    if (c == 0) {
        // First visit
        Tree var, body;
        if (isRec(t, var, body)) {
            // special case for recursive trees
            setProperty(t, k, tree(1));
            annotate(k, body, foo);
            return;
        } else {
            int n = t->arity();
            if (n > 0 && !foo(t)) {
                for (int i = 0; i < n; i++) {
                    annotate(k, t->branch(i), foo);
                }
            }
        }
    } else {
        // printf(" annotate %p with %d\n", t, c+1);
    }
    setProperty(t, k, tree(c + 1));
}
