From 03d5fb1244268fff521df5c2e7d89c6d1361d5a7 Mon Sep 17 00:00:00 2001
From: Renata Hodovan <reni@inf.u-szeged.hu>
Date: Thu, 11 Aug 2016 00:49:45 +0200
Subject: [PATCH] Make Python targets more pythonic.

The Python implementations are completely synchronous
with the Java version even if some of the constructs
can be expressed with simpler Python solutions. These are
typically the all, any, count, next builtins or the list
comprehensions, etc. Beside using them makes the code
clearer, they are also prefered by the standard and can
result in performance speedup. The patch contains such
equivalent transformations in the Python targets.
---
 runtime/Python2/src/antlr4/IntervalSet.py     | 12 ++---
 runtime/Python2/src/antlr4/ListTokenSource.py |  4 +-
 .../Python2/src/antlr4/PredictionContext.py   |  5 +-
 .../Python2/src/antlr4/atn/ATNConfigSet.py    | 23 +++------
 runtime/Python2/src/antlr4/atn/ATNState.py    |  5 +-
 .../src/antlr4/atn/LexerATNSimulator.py       |  6 +--
 .../Python2/src/antlr4/atn/PredictionMode.py  | 47 +++++-------------
 .../Python2/src/antlr4/atn/SemanticContext.py | 37 ++++----------
 runtime/Python2/src/antlr4/dfa/DFAState.py    |  9 +---
 runtime/Python2/src/antlr4/tree/Trees.py      |  3 +-
 runtime/Python2/src/antlr4/xpath/XPath.py     | 17 ++-----
 runtime/Python3/src/antlr4/IntervalSet.py     | 12 ++---
 runtime/Python3/src/antlr4/ListTokenSource.py |  4 +-
 .../Python3/src/antlr4/PredictionContext.py   |  5 +-
 .../Python3/src/antlr4/atn/ATNConfigSet.py    | 23 +++------
 runtime/Python3/src/antlr4/atn/ATNState.py    |  5 +-
 .../src/antlr4/atn/LexerATNSimulator.py       |  6 +--
 .../Python3/src/antlr4/atn/PredictionMode.py  | 48 +++++--------------
 .../Python3/src/antlr4/atn/SemanticContext.py | 38 +++++----------
 runtime/Python3/src/antlr4/dfa/DFAState.py    |  9 +---
 runtime/Python3/src/antlr4/tree/Trees.py      |  3 +-
 runtime/Python3/src/antlr4/xpath/XPath.py     | 16 ++-----
 22 files changed, 88 insertions(+), 249 deletions(-)

diff --git a/runtime/Python2/src/antlr4/IntervalSet.py b/runtime/Python2/src/antlr4/IntervalSet.py
index e28a556d4..3a55a2631 100644
--- a/runtime/Python2/src/antlr4/IntervalSet.py
+++ b/runtime/Python2/src/antlr4/IntervalSet.py
@@ -97,16 +97,10 @@ class IntervalSet(object):
         if self.intervals is None:
             return False
         else:
-            for i in self.intervals:
-                if item in i:
-                    return True
-            return False
+            return any(item in i for i in self.intervals)
 
     def __len__(self):
-        xlen = 0
-        for i in self.intervals:
-            xlen += len(i)
-        return xlen
+        return sum(len(i) for i in self.intervals)
 
     def removeRange(self, v):
         if v.start==v.stop-1:
@@ -126,7 +120,7 @@ class IntervalSet(object):
                 # check for included range, remove it
                 elif v.start<=i.start and v.stop>=i.stop:
                     self.intervals.pop(k)
-                    k = k - 1 # need another pass
+                    k -= 1 # need another pass
                 # check for lower boundary
                 elif v.start<i.stop:
                     self.intervals[k] = Interval(i.start, v.start)
diff --git a/runtime/Python2/src/antlr4/ListTokenSource.py b/runtime/Python2/src/antlr4/ListTokenSource.py
index 5e5e03a02..52c7bb500 100644
--- a/runtime/Python2/src/antlr4/ListTokenSource.py
+++ b/runtime/Python2/src/antlr4/ListTokenSource.py
@@ -101,9 +101,7 @@ class ListTokenSource(TokenSource):
             line = lastToken.line
             tokenText = lastToken.text
             if tokenText is not None:
-                for c in tokenText:
-                    if c  == '\n':
-                        line += 1
+                line += tokenText.count('\n')
 
             # if no text is available, assume the token did not contain any newline characters.
             return line
diff --git a/runtime/Python2/src/antlr4/PredictionContext.py b/runtime/Python2/src/antlr4/PredictionContext.py
index dae19e9e0..44d382818 100644
--- a/runtime/Python2/src/antlr4/PredictionContext.py
+++ b/runtime/Python2/src/antlr4/PredictionContext.py
@@ -585,15 +585,14 @@ def getCachedPredictionContext(context, contextCache, visited):
         parent = getCachedPredictionContext(context.getParent(i), contextCache, visited)
         if changed or parent is not context.getParent(i):
             if not changed:
-                parents = [None] * len(context)
-                for j in range(0, len(context)):
-                    parents[j] = context.getParent(j)
+                parents = [context.getParent(j) for j in range(len(context))]
                 changed = True
             parents[i] = parent
     if not changed:
         contextCache.add(context)
         visited[context] = context
         return context
+
     updated = None
     if len(parents) == 0:
         updated = PredictionContext.EMPTY
diff --git a/runtime/Python2/src/antlr4/atn/ATNConfigSet.py b/runtime/Python2/src/antlr4/atn/ATNConfigSet.py
index d5a73eb38..a59ada670 100755
--- a/runtime/Python2/src/antlr4/atn/ATNConfigSet.py
+++ b/runtime/Python2/src/antlr4/atn/ATNConfigSet.py
@@ -33,6 +33,7 @@
 # info about the set, with support for combining similar configurations using a
 # graph-structured stack.
 #/
+from functools import reduce
 from io import StringIO
 from antlr4.PredictionContext import merge
 from antlr4.Utils import str_list
@@ -118,9 +119,9 @@ class ATNConfigSet(object):
         h = config.hashCodeForConfigSet()
         l = self.configLookup.get(h, None)
         if l is not None:
-            for c in l:
-                if config.equalsForConfigSet(c):
-                    return c
+            r = next((c for c in l if config.equalsForConfigSet(c)), None)
+            if r is not None:
+                return r
         if l is None:
             l = [config]
             self.configLookup[h] = l
@@ -129,17 +130,10 @@ class ATNConfigSet(object):
         return config
 
     def getStates(self):
-        states = set()
-        for c in self.configs:
-            states.add(c.state)
-        return states
+        return set(cfg.state for cfg in self.configs)
 
     def getPredicates(self):
-        preds = list()
-        for c in self.configs:
-            if c.semanticContext!=SemanticContext.NONE:
-                preds.append(c.semanticContext)
-        return preds
+        return [cfg.semanticContext for cfg in self.configs if cfg.semanticContext!=SemanticContext.NONE]
 
     def get(self, i):
         return self.configs[i]
@@ -181,10 +175,7 @@ class ATNConfigSet(object):
         return self.hashConfigs()
 
     def hashConfigs(self):
-        h = 0
-        for cfg in self.configs:
-            h = hash((h, cfg))
-        return h
+        return reduce(lambda h, cfg: hash((h, cfg)), self.configs, 0)
 
     def __len__(self):
         return len(self.configs)
diff --git a/runtime/Python2/src/antlr4/atn/ATNState.py b/runtime/Python2/src/antlr4/atn/ATNState.py
index 36b8d92f3..d10e22ddb 100644
--- a/runtime/Python2/src/antlr4/atn/ATNState.py
+++ b/runtime/Python2/src/antlr4/atn/ATNState.py
@@ -141,10 +141,7 @@ class ATNState(object):
         return self.stateNumber
 
     def __eq__(self, other):
-        if isinstance(other, ATNState):
-            return self.stateNumber==other.stateNumber
-        else:
-            return False
+        return isinstance(other, ATNState) and self.stateNumber==other.stateNumber
 
     def onlyHasEpsilonTransitions(self):
         return self.epsilonOnlyTransitions
diff --git a/runtime/Python2/src/antlr4/atn/LexerATNSimulator.py b/runtime/Python2/src/antlr4/atn/LexerATNSimulator.py
index e847d08f4..2dfa131bb 100644
--- a/runtime/Python2/src/antlr4/atn/LexerATNSimulator.py
+++ b/runtime/Python2/src/antlr4/atn/LexerATNSimulator.py
@@ -535,11 +535,7 @@ class LexerATNSimulator(ATNSimulator):
     def addDFAState(self, configs):
 
         proposed = DFAState(configs=configs)
-        firstConfigWithRuleStopState = None
-        for c in configs:
-            if isinstance(c.state, RuleStopState):
-                firstConfigWithRuleStopState = c
-                break
+        firstConfigWithRuleStopState = next((cfg for cfg in configs if isinstance(cfg.state, RuleStopState)), None)
 
         if firstConfigWithRuleStopState is not None:
             proposed.isAcceptState = True
diff --git a/runtime/Python2/src/antlr4/atn/PredictionMode.py b/runtime/Python2/src/antlr4/atn/PredictionMode.py
index 14280a5b7..0980ba773 100644
--- a/runtime/Python2/src/antlr4/atn/PredictionMode.py
+++ b/runtime/Python2/src/antlr4/atn/PredictionMode.py
@@ -232,10 +232,7 @@ class PredictionMode(object):
     # {@link RuleStopState}, otherwise {@code false}
     @classmethod
     def hasConfigInRuleStopState(cls, configs):
-        for c in configs:
-            if isinstance(c.state, RuleStopState):
-                return True
-        return False
+        return any(isinstance(cfg.state, RuleStopState) for cfg in configs)
 
     # Checks if all configurations in {@code configs} are in a
     # {@link RuleStopState}. Configurations meeting this condition have reached
@@ -247,10 +244,7 @@ class PredictionMode(object):
     # {@link RuleStopState}, otherwise {@code false}
     @classmethod
     def allConfigsInRuleStopStates(cls, configs):
-        for config in configs:
-            if not isinstance(config.state, RuleStopState):
-                return False
-        return True
+        return all(isinstance(cfg.state, RuleStopState) for cfg in configs)
 
     #
     # Full LL prediction termination.
@@ -419,10 +413,7 @@ class PredictionMode(object):
     #
     @classmethod
     def hasNonConflictingAltSet(cls, altsets):
-        for alts in altsets:
-            if len(alts)==1:
-                return True
-        return False
+        return any(len(alts) == 1 for alts in altsets)
 
     #
     # Determines if any single alternative subset in {@code altsets} contains
@@ -434,10 +425,7 @@ class PredictionMode(object):
     #
     @classmethod
     def hasConflictingAltSet(cls, altsets):
-        for alts in altsets:
-            if len(alts)>1:
-                return True
-        return False
+        return any(len(alts) > 1 for alts in altsets)
 
     #
     # Determines if every alternative subset in {@code altsets} is equivalent.
@@ -448,13 +436,9 @@ class PredictionMode(object):
     #
     @classmethod
     def allSubsetsEqual(cls, altsets):
-        first = None
-        for alts in altsets:
-            if first is None:
-                first = alts
-            elif not alts==first:
-                return False
-        return True
+        if not altsets:
+            return True
+        return all(alts == altsets[0] for alts in altsets[1:])
 
     #
     # Returns the unique alternative predicted by all alternative subsets in
@@ -467,10 +451,8 @@ class PredictionMode(object):
     def getUniqueAlt(cls, altsets):
         all = cls.getAlts(altsets)
         if len(all)==1:
-            for one in all:
-                return one
-        else:
-            return ATN.INVALID_ALT_NUMBER
+            return all.pop()
+        return ATN.INVALID_ALT_NUMBER
 
     # Gets the complete set of represented alternatives for a collection of
     # alternative subsets. This method returns the union of each {@link BitSet}
@@ -481,10 +463,7 @@ class PredictionMode(object):
     #
     @classmethod
     def getAlts(cls, altsets):
-        all = set()
-        for alts in altsets:
-            all = all | alts
-        return all
+        return set.union(*altsets)
 
     #
     # This function gets the conflicting alt subsets from a configuration set.
@@ -528,11 +507,7 @@ class PredictionMode(object):
 
     @classmethod
     def hasStateAssociatedWithOneAlt(cls, configs):
-        x = cls.getStateToAltMap(configs)
-        for alts in x.values():
-            if len(alts)==1:
-                return True
-        return False
+        return any(len(alts) == 1 for alts in cls.getStateToAltMap(configs).values())
 
     @classmethod
     def getSingleViableAlt(cls, altsets):
diff --git a/runtime/Python2/src/antlr4/atn/SemanticContext.py b/runtime/Python2/src/antlr4/atn/SemanticContext.py
index 021d4770c..b8fe7b1a0 100644
--- a/runtime/Python2/src/antlr4/atn/SemanticContext.py
+++ b/runtime/Python2/src/antlr4/atn/SemanticContext.py
@@ -115,14 +115,7 @@ def orContext(a, b):
         return result
 
 def filterPrecedencePredicates(collection):
-    result = []
-    for context in collection:
-        if isinstance(context, PrecedencePredicate):
-            if result is None:
-                result = []
-            result.append(context)
-    return result
-
+    return [context for context in collection if isinstance(context, PrecedencePredicate)]
 
 class Predicate(SemanticContext):
 
@@ -187,13 +180,11 @@ class AND(SemanticContext):
     def __init__(self, a, b):
         operands = set()
         if isinstance( a, AND):
-            for o in a.opnds:
-                operands.add(o)
+            operands.update(a.opnds)
         else:
             operands.add(a)
         if isinstance( b, AND):
-            for o in b.opnds:
-                operands.add(o)
+            operands.update(b.opnds)
         else:
             operands.add(b)
 
@@ -203,7 +194,7 @@ class AND(SemanticContext):
             reduced = min(precedencePredicates)
             operands.add(reduced)
 
-        self.opnds = [ o for o in operands ]
+        self.opnds = list(operands)
 
     def __eq__(self, other):
         if self is other:
@@ -227,10 +218,7 @@ class AND(SemanticContext):
     # unordered.</p>
     #
     def eval(self, parser, outerContext):
-        for opnd in self.opnds:
-            if not opnd.eval(parser, outerContext):
-                return False
-        return True
+        return all(opnd.eval(parser, outerContext) for opnd in self.opnds)
 
     def evalPrecedence(self, parser, outerContext):
         differs = False
@@ -277,13 +265,11 @@ class OR (SemanticContext):
     def __init__(self, a, b):
         operands = set()
         if isinstance( a, OR):
-            for o in a.opnds:
-                operands.add(o)
+            operands.update(a.opnds)
         else:
             operands.add(a)
         if isinstance( b, OR):
-            for o in b.opnds:
-                operands.add(o)
+            operands.update(b.opnds)
         else:
             operands.add(b)
 
@@ -291,10 +277,10 @@ class OR (SemanticContext):
         if len(precedencePredicates)>0:
             # interested in the transition with the highest precedence
             s = sorted(precedencePredicates)
-            reduced = s[len(s)-1]
+            reduced = s[-1]
             operands.add(reduced)
 
-        self.opnds = [ o for o in operands ]
+        self.opnds = list(operands)
 
     def __eq__(self, other):
         if self is other:
@@ -315,10 +301,7 @@ class OR (SemanticContext):
     # unordered.</p>
     #
     def eval(self, parser, outerContext):
-        for opnd in self.opnds:
-            if opnd.eval(parser, outerContext):
-                return True
-        return False
+        return any(opnd.eval(parser, outerContext) for opnd in self.opnds)
 
     def evalPrecedence(self, parser, outerContext):
         differs = False
diff --git a/runtime/Python2/src/antlr4/dfa/DFAState.py b/runtime/Python2/src/antlr4/dfa/DFAState.py
index 85ccac106..7045f7c22 100644
--- a/runtime/Python2/src/antlr4/dfa/DFAState.py
+++ b/runtime/Python2/src/antlr4/dfa/DFAState.py
@@ -105,14 +105,9 @@ class DFAState(object):
     # Get the set of all alts mentioned by all ATN configurations in this
     #  DFA state.
     def getAltSet(self):
-        alts = set()
         if self.configs is not None:
-            for c in self.configs:
-                alts.add(c.alt)
-        if len(alts)==0:
-            return None
-        else:
-            return alts
+            return set(cfg.alt for cfg in self.configs) or None
+        return None
 
     def __hash__(self):
         return hash(self.configs)
diff --git a/runtime/Python2/src/antlr4/tree/Trees.py b/runtime/Python2/src/antlr4/tree/Trees.py
index d48f4a904..00a322b45 100644
--- a/runtime/Python2/src/antlr4/tree/Trees.py
+++ b/runtime/Python2/src/antlr4/tree/Trees.py
@@ -129,8 +129,7 @@ class Trees(object):
 
     @classmethod
     def descendants(cls, t):
-        nodes = []
-        nodes.append(t)
+        nodes = [t]
         for i in range(0, t.getChildCount()):
             nodes.extend(cls.descendants(t.getChild(i)))
         return nodes
diff --git a/runtime/Python2/src/antlr4/xpath/XPath.py b/runtime/Python2/src/antlr4/xpath/XPath.py
index eee87da6f..e138d3cdf 100644
--- a/runtime/Python2/src/antlr4/xpath/XPath.py
+++ b/runtime/Python2/src/antlr4/xpath/XPath.py
@@ -289,12 +289,7 @@ class XPathRuleElement(XPathElement):
 
     def evaluate(self, t):
         # return all children of t that match nodeName
-        nodes = []
-        for c in Trees.getChildren(t):
-            if isinstance(c, ParserRuleContext ):
-                if (c.ruleIndex == self.ruleIndex ) == (not self.invert):
-                    nodes.append(c)
-        return nodes
+        return [c for c in Trees.getChildren(t) if isinstance(c, ParserRuleContext) and (c.ruleIndex == self.ruleIndex) == (not self.invert)]
 
 class XPathTokenAnywhereElement(XPathElement):
 
@@ -314,12 +309,8 @@ class XPathTokenElement(XPathElement):
 
     def evaluate(self, t):
         # return all children of t that match nodeName
-        nodes = []
-        for c in Trees.getChildren(t):
-            if isinstance(c, TerminalNode):
-                if (c.symbol.type == self.tokenType ) == (not self.invert):
-                    nodes.append(c)
-        return nodes
+        return [c for c in Trees.getChildren(t) if isinstance(c, TerminalNode) and (c.symbol.type == self.tokenType) == (not self.invert)]
+
 
 class XPathWildcardAnywhereElement(XPathElement):
 
@@ -343,4 +334,4 @@ class XPathWildcardElement(XPathElement):
         if self.invert:
             return list() # !* is weird but valid (empty)
         else:
-            return Trees.getChildren(t)
\ No newline at end of file
+            return Trees.getChildren(t)
diff --git a/runtime/Python3/src/antlr4/IntervalSet.py b/runtime/Python3/src/antlr4/IntervalSet.py
index e5f535f45..980509821 100644
--- a/runtime/Python3/src/antlr4/IntervalSet.py
+++ b/runtime/Python3/src/antlr4/IntervalSet.py
@@ -84,16 +84,10 @@ class IntervalSet(object):
         if self.intervals is None:
             return False
         else:
-            for i in self.intervals:
-                if item in i:
-                    return True
-            return False
+            return any(item in i for i in self.intervals)
 
     def __len__(self):
-        xlen = 0
-        for i in self.intervals:
-            xlen += len(i)
-        return xlen
+        return sum(len(i) for i in self.intervals)
 
     def removeRange(self, v):
         if v.start==v.stop-1:
@@ -113,7 +107,7 @@ class IntervalSet(object):
                 # check for included range, remove it
                 elif v.start<=i.start and v.stop>=i.stop:
                     self.intervals.pop(k)
-                    k = k - 1 # need another pass
+                    k -= 1  # need another pass
                 # check for lower boundary
                 elif v.start<i.stop:
                     self.intervals[k] = range(i.start, v.start)
diff --git a/runtime/Python3/src/antlr4/ListTokenSource.py b/runtime/Python3/src/antlr4/ListTokenSource.py
index c0b929a8d..748085b99 100644
--- a/runtime/Python3/src/antlr4/ListTokenSource.py
+++ b/runtime/Python3/src/antlr4/ListTokenSource.py
@@ -101,9 +101,7 @@ class ListTokenSource(TokenSource):
             line = lastToken.line
             tokenText = lastToken.text
             if tokenText is not None:
-                for c in tokenText:
-                    if c  == '\n':
-                        line += 1
+                line += tokenText.count('\n')
 
             # if no text is available, assume the token did not contain any newline characters.
             return line
diff --git a/runtime/Python3/src/antlr4/PredictionContext.py b/runtime/Python3/src/antlr4/PredictionContext.py
index 6cfc08052..0cfc8896c 100644
--- a/runtime/Python3/src/antlr4/PredictionContext.py
+++ b/runtime/Python3/src/antlr4/PredictionContext.py
@@ -581,15 +581,14 @@ def getCachedPredictionContext(context:PredictionContext, contextCache:Predictio
         parent = getCachedPredictionContext(context.getParent(i), contextCache, visited)
         if changed or parent is not context.getParent(i):
             if not changed:
-                parents = [None] * len(context)
-                for j in range(0, len(context)):
-                    parents[j] = context.getParent(j)
+                parents = [context.getParent(j) for j in range(len(context))]
                 changed = True
             parents[i] = parent
     if not changed:
         contextCache.add(context)
         visited[context] = context
         return context
+
     updated = None
     if len(parents) == 0:
         updated = PredictionContext.EMPTY
diff --git a/runtime/Python3/src/antlr4/atn/ATNConfigSet.py b/runtime/Python3/src/antlr4/atn/ATNConfigSet.py
index e499ac947..8145bb466 100755
--- a/runtime/Python3/src/antlr4/atn/ATNConfigSet.py
+++ b/runtime/Python3/src/antlr4/atn/ATNConfigSet.py
@@ -34,6 +34,7 @@
 # graph-structured stack.
 #/
 from io import StringIO
+from functools import reduce
 from antlr4.PredictionContext import PredictionContext, merge
 from antlr4.Utils import str_list
 from antlr4.atn.ATN import ATN
@@ -121,9 +122,9 @@ class ATNConfigSet(object):
         h = config.hashCodeForConfigSet()
         l = self.configLookup.get(h, None)
         if l is not None:
-            for c in l:
-                if config.equalsForConfigSet(c):
-                    return c
+            r = next((cfg for cfg in l if config.equalsForConfigSet(cfg)), None)
+            if r is not None:
+                return r
         if l is None:
             l = [config]
             self.configLookup[h] = l
@@ -132,17 +133,10 @@ class ATNConfigSet(object):
         return config
 
     def getStates(self):
-        states = set()
-        for c in self.configs:
-            states.add(c.state)
-        return states
+        return set(c.state for c in self.configs)
 
     def getPredicates(self):
-        preds = list()
-        for c in self.configs:
-            if c.semanticContext!=SemanticContext.NONE:
-                preds.append(c.semanticContext)
-        return preds
+        return list(cfg.semanticContext for cfg in self.configs if cfg.semanticContext!=SemanticContext.NONE)
 
     def get(self, i:int):
         return self.configs[i]
@@ -184,10 +178,7 @@ class ATNConfigSet(object):
         return self.hashConfigs()
 
     def hashConfigs(self):
-        h = 0
-        for cfg in self.configs:
-            h = hash((h, cfg))
-        return h
+        return reduce(lambda h, cfg: hash((h, cfg)), self.configs, 0)
 
     def __len__(self):
         return len(self.configs)
diff --git a/runtime/Python3/src/antlr4/atn/ATNState.py b/runtime/Python3/src/antlr4/atn/ATNState.py
index 446512193..6dd89f020 100644
--- a/runtime/Python3/src/antlr4/atn/ATNState.py
+++ b/runtime/Python3/src/antlr4/atn/ATNState.py
@@ -143,10 +143,7 @@ class ATNState(object):
         return self.stateNumber
 
     def __eq__(self, other):
-        if isinstance(other, ATNState):
-            return self.stateNumber==other.stateNumber
-        else:
-            return False
+        return isinstance(other, ATNState) and self.stateNumber==other.stateNumber
 
     def onlyHasEpsilonTransitions(self):
         return self.epsilonOnlyTransitions
diff --git a/runtime/Python3/src/antlr4/atn/LexerATNSimulator.py b/runtime/Python3/src/antlr4/atn/LexerATNSimulator.py
index 9e7cff144..f5a649a94 100644
--- a/runtime/Python3/src/antlr4/atn/LexerATNSimulator.py
+++ b/runtime/Python3/src/antlr4/atn/LexerATNSimulator.py
@@ -542,11 +542,7 @@ class LexerATNSimulator(ATNSimulator):
     def addDFAState(self, configs:ATNConfigSet) -> DFAState:
 
         proposed = DFAState(configs=configs)
-        firstConfigWithRuleStopState = None
-        for c in configs:
-            if isinstance(c.state, RuleStopState):
-                firstConfigWithRuleStopState = c
-                break
+        firstConfigWithRuleStopState = next((cfg for cfg in configs if isinstance(cfg.state, RuleStopState)), None)
 
         if firstConfigWithRuleStopState is not None:
             proposed.isAcceptState = True
diff --git a/runtime/Python3/src/antlr4/atn/PredictionMode.py b/runtime/Python3/src/antlr4/atn/PredictionMode.py
index 03ca896c7..67039c728 100644
--- a/runtime/Python3/src/antlr4/atn/PredictionMode.py
+++ b/runtime/Python3/src/antlr4/atn/PredictionMode.py
@@ -235,10 +235,7 @@ class PredictionMode(Enum):
     # {@link RuleStopState}, otherwise {@code false}
     @classmethod
     def hasConfigInRuleStopState(cls, configs:ATNConfigSet):
-        for c in configs:
-            if isinstance(c.state, RuleStopState):
-                return True
-        return False
+        return any(isinstance(cfg.state, RuleStopState) for cfg in configs)
 
     # Checks if all configurations in {@code configs} are in a
     # {@link RuleStopState}. Configurations meeting this condition have reached
@@ -250,10 +247,7 @@ class PredictionMode(Enum):
     # {@link RuleStopState}, otherwise {@code false}
     @classmethod
     def allConfigsInRuleStopStates(cls, configs:ATNConfigSet):
-        for config in configs:
-            if not isinstance(config.state, RuleStopState):
-                return False
-        return True
+        return all(isinstance(cfg.state, RuleStopState) for cfg in configs)
 
     #
     # Full LL prediction termination.
@@ -422,10 +416,7 @@ class PredictionMode(Enum):
     #
     @classmethod
     def hasNonConflictingAltSet(cls, altsets:list):
-        for alts in altsets:
-            if len(alts)==1:
-                return True
-        return False
+        return any(len(alts) == 1 for alts in altsets)
 
     #
     # Determines if any single alternative subset in {@code altsets} contains
@@ -437,10 +428,7 @@ class PredictionMode(Enum):
     #
     @classmethod
     def hasConflictingAltSet(cls, altsets:list):
-        for alts in altsets:
-            if len(alts)>1:
-                return True
-        return False
+        return any(len(alts) > 1 for alts in altsets)
 
     #
     # Determines if every alternative subset in {@code altsets} is equivalent.
@@ -451,13 +439,10 @@ class PredictionMode(Enum):
     #
     @classmethod
     def allSubsetsEqual(cls, altsets:list):
-        first = None
-        for alts in altsets:
-            if first is None:
-                first = alts
-            elif not alts==first:
-                return False
-        return True
+        if not altsets:
+            return True
+        first = next(iter(altsets))
+        return all(alts == first for alts in iter(altsets))
 
     #
     # Returns the unique alternative predicted by all alternative subsets in
@@ -470,10 +455,8 @@ class PredictionMode(Enum):
     def getUniqueAlt(cls, altsets:list):
         all = cls.getAlts(altsets)
         if len(all)==1:
-            for one in all:
-                return one
-        else:
-            return ATN.INVALID_ALT_NUMBER
+            return next(iter(all))
+        return ATN.INVALID_ALT_NUMBER
 
     # Gets the complete set of represented alternatives for a collection of
     # alternative subsets. This method returns the union of each {@link BitSet}
@@ -484,10 +467,7 @@ class PredictionMode(Enum):
     #
     @classmethod
     def getAlts(cls, altsets:list):
-        all = set()
-        for alts in altsets:
-            all = all | alts
-        return all
+        return set.union(*altsets)
 
     #
     # This function gets the conflicting alt subsets from a configuration set.
@@ -531,11 +511,7 @@ class PredictionMode(Enum):
 
     @classmethod
     def hasStateAssociatedWithOneAlt(cls, configs:ATNConfigSet):
-        x = cls.getStateToAltMap(configs)
-        for alts in x.values():
-            if len(alts)==1:
-                return True
-        return False
+        return any(len(alts) == 1 for alts in cls.getStateToAltMap(configs).values())
 
     @classmethod
     def getSingleViableAlt(cls, altsets:list):
diff --git a/runtime/Python3/src/antlr4/atn/SemanticContext.py b/runtime/Python3/src/antlr4/atn/SemanticContext.py
index c012e35c2..d69165e4d 100644
--- a/runtime/Python3/src/antlr4/atn/SemanticContext.py
+++ b/runtime/Python3/src/antlr4/atn/SemanticContext.py
@@ -116,13 +116,7 @@ def orContext(a:SemanticContext, b:SemanticContext):
         return result
 
 def filterPrecedencePredicates(collection:list):
-    result = []
-    for context in collection:
-        if isinstance(context, PrecedencePredicate):
-            if result is None:
-                result = []
-            result.append(context)
-    return result
+    return [context for context in collection if isinstance(context, PrecedencePredicate)]
 
 
 class Predicate(SemanticContext):
@@ -188,13 +182,11 @@ class AND(SemanticContext):
     def __init__(self, a:SemanticContext, b:SemanticContext):
         operands = set()
         if isinstance( a, AND ):
-            for o in a.opnds:
-                operands.add(o)
+            operands.update(a.opnds)
         else:
             operands.add(a)
         if isinstance( b, AND ):
-            for o in b.opnds:
-                operands.add(o)
+            operands.update(b.opnds)
         else:
             operands.add(b)
 
@@ -204,7 +196,7 @@ class AND(SemanticContext):
             reduced = min(precedencePredicates)
             operands.add(reduced)
 
-        self.opnds = [ o for o in operands ]
+        self.opnds = list(operands)
 
     def __eq__(self, other):
         if self is other:
@@ -227,11 +219,8 @@ class AND(SemanticContext):
     # The evaluation of predicates by this context is short-circuiting, but
     # unordered.</p>
     #
-    def eval(self, parser:Recognizer , outerContext:RuleContext ):
-        for opnd in self.opnds:
-            if not opnd.eval(parser, outerContext):
-                return False
-        return True
+    def eval(self, parser:Recognizer, outerContext:RuleContext):
+        return all(opnd.eval(parser, outerContext) for opnd in self.opnds)
 
     def evalPrecedence(self, parser:Recognizer, outerContext:RuleContext):
         differs = False
@@ -278,13 +267,11 @@ class OR (SemanticContext):
     def __init__(self, a:SemanticContext, b:SemanticContext):
         operands = set()
         if isinstance( a, OR ):
-            for o in a.opnds:
-                operands.add(o)
+            operands.update(a.opnds)
         else:
             operands.add(a)
         if isinstance( b, OR ):
-            for o in b.opnds:
-                operands.add(o)
+            operands.update(b.opnds)
         else:
             operands.add(b)
 
@@ -292,10 +279,10 @@ class OR (SemanticContext):
         if len(precedencePredicates)>0:
             # interested in the transition with the highest precedence
             s = sorted(precedencePredicates)
-            reduced = s[len(s)-1]
+            reduced = s[-1]
             operands.add(reduced)
 
-        self.opnds = [ o for o in operands ]
+        self.opnds = list(operands)
 
     def __eq__(self, other):
         if self is other:
@@ -316,10 +303,7 @@ class OR (SemanticContext):
     # unordered.</p>
     #
     def eval(self, parser:Recognizer, outerContext:RuleContext):
-        for opnd in self.opnds:
-            if opnd.eval(parser, outerContext):
-                return True
-        return False
+        return any(opnd.eval(parser, outerContext) for opnd in self.opnds)
 
     def evalPrecedence(self, parser:Recognizer, outerContext:RuleContext):
         differs = False
diff --git a/runtime/Python3/src/antlr4/dfa/DFAState.py b/runtime/Python3/src/antlr4/dfa/DFAState.py
index 1ab5a0e77..9ad996384 100644
--- a/runtime/Python3/src/antlr4/dfa/DFAState.py
+++ b/runtime/Python3/src/antlr4/dfa/DFAState.py
@@ -104,14 +104,9 @@ class DFAState(object):
     # Get the set of all alts mentioned by all ATN configurations in this
     #  DFA state.
     def getAltSet(self):
-        alts = set()
         if self.configs is not None:
-            for c in self.configs:
-                alts.add(c.alt)
-        if len(alts)==0:
-            return None
-        else:
-            return alts
+            return set(cfg.alt for cfg in self.configs) or None
+        return None
 
     def __hash__(self):
         return hash(self.configs)
diff --git a/runtime/Python3/src/antlr4/tree/Trees.py b/runtime/Python3/src/antlr4/tree/Trees.py
index 101df6d9a..42fde282b 100644
--- a/runtime/Python3/src/antlr4/tree/Trees.py
+++ b/runtime/Python3/src/antlr4/tree/Trees.py
@@ -130,8 +130,7 @@ class Trees(object):
 
     @classmethod
     def descendants(cls, t:ParseTree):
-        nodes = []
-        nodes.append(t)
+        nodes = [t]
         for i in range(0, t.getChildCount()):
             nodes.extend(cls.descendants(t.getChild(i)))
         return nodes
diff --git a/runtime/Python3/src/antlr4/xpath/XPath.py b/runtime/Python3/src/antlr4/xpath/XPath.py
index 6b41a943a..6d3d825a5 100644
--- a/runtime/Python3/src/antlr4/xpath/XPath.py
+++ b/runtime/Python3/src/antlr4/xpath/XPath.py
@@ -290,12 +290,8 @@ class XPathRuleElement(XPathElement):
 
     def evaluate(self, t:ParseTree):
         # return all children of t that match nodeName
-        nodes = []
-        for c in Trees.getChildren(t):
-            if isinstance(c, ParserRuleContext ):
-                if (c.ruleIndex == self.ruleIndex ) == (not self.invert):
-                    nodes.append(c)
-        return nodes
+        return [c for c in Trees.getChildren(t) if isinstance(c, ParserRuleContext) and (c.ruleIndex == self.ruleIndex) == (not self.invert)]
+
 
 class XPathTokenAnywhereElement(XPathElement):
 
@@ -315,12 +311,8 @@ class XPathTokenElement(XPathElement):
 
     def evaluate(self, t:ParseTree):
         # return all children of t that match nodeName
-        nodes = []
-        for c in Trees.getChildren(t):
-            if isinstance(c, TerminalNode):
-                if (c.symbol.type == self.tokenType ) == (not self.invert):
-                    nodes.append(c)
-        return nodes
+        return [c for c in Trees.getChildren(t) if isinstance(c, TerminalNode) and (c.symbol.type == self.tokenType) == (not self.invert)]
+
 
 class XPathWildcardAnywhereElement(XPathElement):