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| author | jblum <jblum@221aa14e-8319-0410-a670-987f0aec2ac5> | 2008-09-07 21:38:12 +0000 |
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| committer | jblum <jblum@221aa14e-8319-0410-a670-987f0aec2ac5> | 2008-09-07 21:38:12 +0000 |
| commit | c86f6c23c6883f73d953d64c28ab42cedb77e4d7 (patch) | |
| tree | 0193b2a649eb0f7f1065912862de340a02848e16 /grc/src/platforms/python/utils/expr_utils.py | |
| parent | ddec4fc07744a6519086b1b111f29d551b7f19c6 (diff) | |
Merged r9481:9518 on jblum/grc_reorganize into trunk. Reorganized grc source under gnuradio.grc module. Trunk passes make distcheck.
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@9525 221aa14e-8319-0410-a670-987f0aec2ac5
Diffstat (limited to 'grc/src/platforms/python/utils/expr_utils.py')
| -rw-r--r-- | grc/src/platforms/python/utils/expr_utils.py | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/grc/src/platforms/python/utils/expr_utils.py b/grc/src/platforms/python/utils/expr_utils.py new file mode 100644 index 0000000000..40700993dd --- /dev/null +++ b/grc/src/platforms/python/utils/expr_utils.py @@ -0,0 +1,137 @@ +""" +Copyright 2008 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 self._graph.has_key(node_key): return + self._graph[node_key] = set() + + def remove_node(self, node_key): + if not self._graph.has_key(node_key): 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. + @param expr an expression string + @return 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_prepend(expr, vars, prepend): + """ + Search for vars in the expression and add the prepend. + @param expr an expression string + @param vars a list of variable names + @param prepend the prepend string + @return a new expression with the prepend + """ + expr_splits = expr_split(expr) + for i, es in enumerate(expr_splits): + if es in vars: expr_splits[i] = prepend + es + return ''.join(expr_splits) + +def get_variable_dependencies(expr, vars): + """ + Return a set of variables used in this expression. + @param expr an expression string + @param vars a list of variable names + @return 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 + @param exprs a mapping of variable name to expression + @return 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): + var_graph.add_edge(dep, var) + return var_graph + +def sort_variables(exprs): + """ + Get a list of variables in order of dependencies. + @param exprs a mapping of variable name to expression + @return a list of variable names + @throws AssertionError 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()) + assert indep_vars + #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) + +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 |