Adding bash stack utility only modified to add license.

Signed-off-by: Damian Rouson <[email protected]>

Author: Damian Rouson

install_prerequisites/stack.sh

@@ -0,0 +1,192 @@
+# A stack, using bash arrays.
+# ---------------------------------------------------------------------------
+# This software is released under a BSD license, adapted from
+# <http://opensource.org/licenses/bsd-license.php>
+#
+# Copyright &copy; 1989-2012 Brian M. Clapper.
+# All rights reserved.
+#
+# 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 "clapper.org" 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 HOLDER 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.
+#
+
+# Create a new stack.
+#
+# Usage: stack_new name
+#
+# Example: stack_new x
+function stack_new
+{
+    : ${1?'Missing stack name'}
+    if stack_exists $1
+    then
+        echo "Stack already exists -- $1" >&2
+        return 1
+    fi
+
+    eval "declare -ag _stack_$1"
+    eval "declare -ig _stack_$1_i"
+    eval "let _stack_$1_i=0"
+    return 0
+}
+
+# Destroy a stack
+#
+# Usage: stack_destroy name
+function stack_destroy
+{
+    : ${1?'Missing stack name'}
+    eval "unset _stack_$1 _stack_$1_i"
+    return 0
+}
+
+# Push one or more items onto a stack.
+#
+# Usage: stack_push stack item ...
+function stack_push
+{
+    : ${1?'Missing stack name'}
+    : ${2?'Missing item(s) to push'}
+
+    if no_such_stack $1
+    then
+        echo "No such stack -- $1" >&2
+        return 1
+    fi
+
+    stack=$1
+    shift 1
+
+    while (( $# > 0 ))
+    do
+        eval '_i=$'"_stack_${stack}_i"
+        eval "_stack_${stack}[$_i]='$1'"
+        eval "let _stack_${stack}_i+=1"
+        shift 1
+    done
+
+    unset _i
+    return 0
+}
+
+# Print a stack to stdout.
+#
+# Usage: stack_print name
+function stack_print
+{
+    : ${1?'Missing stack name'}
+
+    if no_such_stack $1
+    then
+        echo "No such stack -- $1" >&2
+        return 1
+    fi
+
+    tmp=""
+    eval 'let _i=$'_stack_$1_i
+    while (( $_i > 0 ))
+    do
+        let _i=${_i}-1
+        eval 'e=$'"{_stack_$1[$_i]}"
+        tmp="$tmp $e"
+    done
+    echo "(" $tmp ")"
+}
+
+# Get the size of a stack
+#
+# Usage: stack_size name var
+#
+# Example:
+#    stack_size mystack n
+#    echo "Size is $n"
+function stack_size
+{
+    : ${1?'Missing stack name'}
+    : ${2?'Missing name of variable for stack size result'}
+    if no_such_stack $1
+    then
+        echo "No such stack -- $1" >&2
+        return 1
+    fi
+    eval "$2"='$'"{#_stack_$1[*]}"
+}
+
+# Pop the top element from the stack.
+#
+# Usage: stack_pop name var
+#
+# Example:
+#    stack_pop mystack top
+#    echo "Got $top"
+function stack_pop
+{
+    : ${1?'Missing stack name'}
+    : ${2?'Missing name of variable for popped result'}
+
+    eval 'let _i=$'"_stack_$1_i"
+    if no_such_stack $1
+    then
+        echo "No such stack -- $1" >&2
+        return 1
+    fi
+
+    if [[ "$_i" -eq 0 ]]
+    then
+        echo "Empty stack -- $1" >&2
+        return 1
+    fi
+
+    let _i-=1
+    eval "$2"='$'"{_stack_$1[$_i]}"
+    eval "unset _stack_$1[$_i]"
+    eval "_stack_$1_i=$_i"
+    unset _i
+    return 0
+}
+
+function no_such_stack
+{
+    : ${1?'Missing stack name'}
+    stack_exists $1
+    ret=$?
+    declare -i x
+    let x="1-$ret"
+    return $x
+}
+
+function stack_exists
+{
+    : ${1?'Missing stack name'}
+
+    eval '_i=$'"_stack_$1_i"
+    if [[ -z "$_i" ]]
+    then
+        return 1
+    else
+        return 0
+    fi
+}