From 9023d2ad1ad5d1704bbe7fe942e42156a1f273a4 Mon Sep 17 00:00:00 2001
From: Sebastian Koslowski <koslowski@kit.edu>
Date: Fri, 5 Feb 2016 16:44:10 +0100
Subject: grc-refactor: cmake fixes and more reorganizing
---
grc/core/utils/expr_utils.py | 196 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 196 insertions(+)
create mode 100644 grc/core/utils/expr_utils.py
(limited to 'grc/core/utils/expr_utils.py')
diff --git a/grc/core/utils/expr_utils.py b/grc/core/utils/expr_utils.py
new file mode 100644
index 0000000000..66911757d6
--- /dev/null
+++ b/grc/core/utils/expr_utils.py
@@ -0,0 +1,196 @@
+"""
+Copyright 2008-2011 Free Software Foundation, Inc.
+This file is part of GNU Radio
+
+GNU Radio Companion is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+GNU Radio Companion 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+"""
+
+import string
+VAR_CHARS = string.letters + string.digits + '_'
+
+
+class graph(object):
+ """
+ Simple graph structure held in a dictionary.
+ """
+
+ def __init__(self): self._graph = dict()
+
+ def __str__(self): return str(self._graph)
+
+ def add_node(self, node_key):
+ if node_key in self._graph:
+ return
+ self._graph[node_key] = set()
+
+ def remove_node(self, node_key):
+ if node_key not in self._graph:
+ return
+ for edges in self._graph.values():
+ if node_key in edges:
+ edges.remove(node_key)
+ self._graph.pop(node_key)
+
+ def add_edge(self, src_node_key, dest_node_key):
+ self._graph[src_node_key].add(dest_node_key)
+
+ def remove_edge(self, src_node_key, dest_node_key):
+ self._graph[src_node_key].remove(dest_node_key)
+
+ def get_nodes(self):
+ return self._graph.keys()
+
+ def get_edges(self, node_key):
+ return self._graph[node_key]
+
+
+def expr_split(expr):
+ """
+ Split up an expression by non alphanumeric characters, including underscore.
+ Leave strings in-tact.
+ #TODO ignore escaped quotes, use raw strings.
+
+ Args:
+ expr: an expression string
+
+ Returns:
+ a list of string tokens that form expr
+ """
+ toks = list()
+ tok = ''
+ quote = ''
+ for char in expr:
+ if quote or char in VAR_CHARS:
+ if char == quote:
+ quote = ''
+ tok += char
+ elif char in ("'", '"'):
+ toks.append(tok)
+ tok = char
+ quote = char
+ else:
+ toks.append(tok)
+ toks.append(char)
+ tok = ''
+ toks.append(tok)
+ return filter(lambda t: t, toks)
+
+
+def expr_replace(expr, replace_dict):
+ """
+ Search for vars in the expression and add the prepend.
+
+ Args:
+ expr: an expression string
+ replace_dict: a dict of find:replace
+
+ Returns:
+ a new expression with the prepend
+ """
+ expr_splits = expr_split(expr)
+ for i, es in enumerate(expr_splits):
+ if es in replace_dict.keys():
+ expr_splits[i] = replace_dict[es]
+ return ''.join(expr_splits)
+
+
+def get_variable_dependencies(expr, vars):
+ """
+ Return a set of variables used in this expression.
+
+ Args:
+ expr: an expression string
+ vars: a list of variable names
+
+ Returns:
+ a subset of vars used in the expression
+ """
+ expr_toks = expr_split(expr)
+ return set(filter(lambda v: v in expr_toks, vars))
+
+
+def get_graph(exprs):
+ """
+ Get a graph representing the variable dependencies
+
+ Args:
+ exprs: a mapping of variable name to expression
+
+ Returns:
+ a graph of variable deps
+ """
+ vars = exprs.keys()
+ # Get dependencies for each expression, load into graph
+ var_graph = graph()
+ for var in vars:
+ var_graph.add_node(var)
+ for var, expr in exprs.iteritems():
+ for dep in get_variable_dependencies(expr, vars):
+ if dep != var:
+ var_graph.add_edge(dep, var)
+ return var_graph
+
+
+def sort_variables(exprs):
+ """
+ Get a list of variables in order of dependencies.
+
+ Args:
+ exprs: a mapping of variable name to expression
+
+ Returns:
+ a list of variable names
+ @throws Exception circular dependencies
+ """
+ var_graph = get_graph(exprs)
+ sorted_vars = list()
+ # Determine dependency order
+ while var_graph.get_nodes():
+ # Get a list of nodes with no edges
+ indep_vars = filter(lambda var: not var_graph.get_edges(var), var_graph.get_nodes())
+ if not indep_vars:
+ raise Exception('circular dependency caught in sort_variables')
+ # Add the indep vars to the end of the list
+ sorted_vars.extend(sorted(indep_vars))
+ # Remove each edge-less node from the graph
+ for var in indep_vars:
+ var_graph.remove_node(var)
+ return reversed(sorted_vars)
+
+
+def sort_objects(objects, get_id, get_expr):
+ """
+ Sort a list of objects according to their expressions.
+
+ Args:
+ objects: the list of objects to sort
+ get_id: the function to extract an id from the object
+ get_expr: the function to extract an expression from the object
+
+ Returns:
+ a list of sorted objects
+ """
+ id2obj = dict([(get_id(obj), obj) for obj in objects])
+ # Map obj id to expression code
+ id2expr = dict([(get_id(obj), get_expr(obj)) for obj in objects])
+ # Sort according to dependency
+ sorted_ids = sort_variables(id2expr)
+ # Return list of sorted objects
+ return [id2obj[id] for id in sorted_ids]
+
+
+if __name__ == '__main__':
+ for i in sort_variables({'x': '1', 'y': 'x+1', 'a': 'x+y', 'b': 'y+1', 'c': 'a+b+x+y'}):
+ print i
--
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