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Expr.java
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Expr.java
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// Copyright 2012 Cloudera Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.cloudera.impala.analysis;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Set;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.cloudera.impala.catalog.Catalog;
import com.cloudera.impala.catalog.Function;
import com.cloudera.impala.catalog.Function.CompareMode;
import com.cloudera.impala.catalog.PrimitiveType;
import com.cloudera.impala.catalog.ScalarType;
import com.cloudera.impala.catalog.Type;
import com.cloudera.impala.common.AnalysisException;
import com.cloudera.impala.common.TreeNode;
import com.cloudera.impala.thrift.TExpr;
import com.cloudera.impala.thrift.TExprNode;
import com.google.common.base.Joiner;
import com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicates;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
/**
* Root of the expr node hierarchy.
*
*/
abstract public class Expr extends TreeNode<Expr> implements ParseNode, Cloneable {
private final static Logger LOG = LoggerFactory.getLogger(Expr.class);
// Limits on the number of expr children and the depth of an expr tree. These maximum
// values guard against crashes due to stack overflows (IMPALA-432) and were
// experimentally determined to be safe.
public final static int EXPR_CHILDREN_LIMIT = 10000;
// The expr depth limit is mostly due to our recursive implementation of clone().
public final static int EXPR_DEPTH_LIMIT = 1500;
// Name of the function that needs to be implemented by every Expr that
// supports negation.
private final static String NEGATE_FN = "negate";
// to be used where we can't come up with a better estimate
protected static double DEFAULT_SELECTIVITY = 0.1;
// returns true if an Expr is a non-analytic aggregate.
private final static com.google.common.base.Predicate<Expr> isAggregatePredicate_ =
new com.google.common.base.Predicate<Expr>() {
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr &&
((FunctionCallExpr)arg).isAggregateFunction();
}
};
// Returns true if an Expr is a NOT CompoundPredicate.
public final static com.google.common.base.Predicate<Expr> IS_NOT_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof CompoundPredicate &&
((CompoundPredicate)arg).getOp() == CompoundPredicate.Operator.NOT;
}
};
// Returns true if an Expr is an OR CompoundPredicate.
public final static com.google.common.base.Predicate<Expr> IS_OR_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof CompoundPredicate &&
((CompoundPredicate)arg).getOp() == CompoundPredicate.Operator.OR;
}
};
// Returns true if an Expr is a scalar subquery
public final static com.google.common.base.Predicate<Expr> IS_SCALAR_SUBQUERY =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg.isScalarSubquery();
}
};
// Returns true if an Expr is an aggregate function that returns non-null on
// an empty set (e.g. count).
public final static com.google.common.base.Predicate<Expr>
NON_NULL_EMPTY_AGG = new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr &&
((FunctionCallExpr)arg).returnsNonNullOnEmpty();
}
};
// Returns true if an Expr is a builtin aggregate function.
public final static com.google.common.base.Predicate<Expr> IS_BUILTIN_AGG_FN =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr &&
((FunctionCallExpr)arg).getFnName().isBuiltin();
}
};
public final static com.google.common.base.Predicate<Expr> IS_TRUE_LITERAL =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof BoolLiteral && ((BoolLiteral)arg).getValue();
}
};
// id that's unique across the entire query statement and is assigned by
// Analyzer.registerConjuncts(); only assigned for the top-level terms of a
// conjunction, and therefore null for most Exprs
protected ExprId id_;
// true if Expr is an auxiliary predicate that was generated by the plan generation
// process to facilitate predicate propagation;
// false if Expr originated with a query stmt directly
private boolean isAuxExpr_ = false;
protected Type type_; // result of analysis
protected boolean isAnalyzed_; // true after analyze() has been called
protected boolean isWhereClauseConjunct_; // set by analyzer
// Flag to indicate whether to wrap this expr's toSql() in parenthesis. Set by parser.
// Needed for properly capturing expr precedences in the SQL string.
protected boolean printSqlInParens_ = false;
// estimated probability of a predicate evaluating to true;
// set during analysis;
// between 0 and 1 if valid: invalid: -1
protected double selectivity_;
// estimated number of distinct values produced by Expr; invalid: -1
// set during analysis
protected long numDistinctValues_;
// The function to call. This can either be a scalar or aggregate function.
// Set in analyze().
protected Function fn_;
protected Expr() {
super();
type_ = Type.INVALID;
selectivity_ = -1.0;
numDistinctValues_ = -1;
}
/**
* Copy c'tor used in clone().
*/
protected Expr(Expr other) {
id_ = other.id_;
isAuxExpr_ = other.isAuxExpr_;
type_ = other.type_;
isAnalyzed_ = other.isAnalyzed_;
isWhereClauseConjunct_ = other.isWhereClauseConjunct_;
printSqlInParens_ = other.printSqlInParens_;
selectivity_ = other.selectivity_;
numDistinctValues_ = other.numDistinctValues_;
fn_ = other.fn_;
children_ = Expr.cloneList(other.children_);
}
public ExprId getId() { return id_; }
protected void setId(ExprId id) { this.id_ = id; }
public Type getType() { return type_; }
public double getSelectivity() { return selectivity_; }
public long getNumDistinctValues() { return numDistinctValues_; }
public void setPrintSqlInParens(boolean b) { printSqlInParens_ = b; }
public boolean isWhereClauseConjunct() { return isWhereClauseConjunct_; }
public void setIsWhereClauseConjunct() { isWhereClauseConjunct_ = true; }
public boolean isAuxExpr() { return isAuxExpr_; }
public void setIsAuxExpr() { isAuxExpr_ = true; }
public Function getFn() { return fn_; }
/**
* Perform semantic analysis of node and all of its children.
* Throws exception if any errors found.
* @see com.cloudera.impala.parser.ParseNode#analyze(com.cloudera.impala.parser.Analyzer)
*/
public void analyze(Analyzer analyzer) throws AnalysisException {
// Check the expr child limit.
if (children_.size() > EXPR_CHILDREN_LIMIT) {
String sql = toSql();
String sqlSubstr = sql.substring(0, Math.min(80, sql.length()));
throw new AnalysisException(String.format("Exceeded the maximum number of child " +
"expressions (%s).\nExpression has %s children:\n%s...",
EXPR_CHILDREN_LIMIT, children_.size(), sqlSubstr));
}
// analyzer may be null for certain literal constructions (e.g. IntLiteral).
if (analyzer != null) {
analyzer.incrementCallDepth();
// Check the expr depth limit. Do not print the toSql() to not overflow the stack.
if (analyzer.getCallDepth() > EXPR_DEPTH_LIMIT) {
throw new AnalysisException(String.format("Exceeded the maximum depth of an " +
"expression tree (%s).", EXPR_DEPTH_LIMIT));
}
}
for (Expr child: children_) {
child.analyze(analyzer);
}
isAnalyzed_ = true;
computeNumDistinctValues();
if (analyzer != null) analyzer.decrementCallDepth();
}
/**
* Helper function to analyze this expr and assert that the analysis was successful.
* TODO: This function could be used in many more places to clean up. Consider
* adding an IAnalyzable interface or similar to and move this helper into Analyzer
* such that non-Expr things can use the helper also.
*/
public void analyzeNoThrow(Analyzer analyzer) {
try {
analyze(analyzer);
} catch (AnalysisException e) {
throw new IllegalStateException(e);
}
}
protected void computeNumDistinctValues() {
if (isConstant()) {
numDistinctValues_ = 1;
} else {
// if this Expr contains slotrefs, we estimate the # of distinct values
// to be the maximum such number for any of the slotrefs;
// the subclass analyze() function may well want to override this, if it
// knows better
List<SlotRef> slotRefs = Lists.newArrayList();
this.collect(Predicates.instanceOf(SlotRef.class), slotRefs);
numDistinctValues_ = -1;
for (SlotRef slotRef: slotRefs) {
numDistinctValues_ = Math.max(numDistinctValues_, slotRef.numDistinctValues_);
}
}
}
/**
* Collects the returns types of the child nodes in an array.
*/
protected Type[] collectChildReturnTypes() {
Type[] childTypes = new Type[children_.size()];
for (int i = 0; i < children_.size(); ++i) {
childTypes[i] = children_.get(i).type_;
}
return childTypes;
}
/**
* Looks up in the catalog the builtin for 'name' and 'argTypes'.
* Returns null if the function is not found.
*/
protected Function getBuiltinFunction(Analyzer analyzer, String name,
Type[] argTypes, CompareMode mode) throws AnalysisException {
FunctionName fnName = new FunctionName(Catalog.BUILTINS_DB, name);
Function searchDesc = new Function(fnName, argTypes, Type.INVALID, false);
return analyzer.getCatalog().getFunction(searchDesc, mode);
}
/**
* Generates the necessary casts for the children of this expr to call fn_.
* child(0) is cast to the function's first argument, child(1) to the second etc.
* This does not do any validation and the casts are assumed to be safe.
*
* If ignoreWildcardDecimals is true, the function will not cast arguments that
* are wildcard decimals. This is used for builtins where the cast is done within
* the BE function.
* Otherwise, if the function signature contains wildcard decimals, each wildcard child
* argument will be cast to the highest resolution that can contain all of the child
* wildcard arguments.
* e.g. fn(decimal(*), decimal(*))
* called with fn(decimal(10,2), decimal(5,3))
* both children will be cast to (11, 3).
*/
protected void castForFunctionCall(boolean ignoreWildcardDecimals)
throws AnalysisException {
Preconditions.checkState(fn_ != null);
Type[] fnArgs = fn_.getArgs();
Type resolvedWildcardType = getResolvedWildCardType();
for (int i = 0; i < children_.size(); ++i) {
// For varargs, we must compare with the last type in fnArgs.argTypes.
int ix = Math.min(fnArgs.length - 1, i);
if (fnArgs[ix].isWildcardDecimal()) {
if (children_.get(i).type_.isDecimal() && ignoreWildcardDecimals) continue;
Preconditions.checkState(resolvedWildcardType != null);
if (!children_.get(i).type_.equals(resolvedWildcardType)) {
castChild(resolvedWildcardType, i);
}
} else if (!children_.get(i).type_.matchesType(fnArgs[ix])) {
castChild(fnArgs[ix], i);
}
}
}
/**
* Returns the max resolution type of all the wild card decimal types.
* Returns null if there are no wild card types.
*/
Type getResolvedWildCardType() throws AnalysisException {
Type result = null;
Type[] fnArgs = fn_.getArgs();
for (int i = 0; i < children_.size(); ++i) {
// For varargs, we must compare with the last type in fnArgs.argTypes.
int ix = Math.min(fnArgs.length - 1, i);
if (!fnArgs[ix].isWildcardDecimal()) continue;
Type childType = children_.get(i).type_;
Preconditions.checkState(!childType.isWildcardDecimal(),
"Child expr should have been resolved.");
Preconditions.checkState(childType.isScalarType(),
"Function should not have resolved with a non-scalar child type.");
ScalarType decimalType = (ScalarType) childType;
if (result == null) {
result = decimalType.getMinResolutionDecimal();
} else {
result = Type.getAssignmentCompatibleType(result, childType);
}
}
if (result != null) {
if (result.isNull()) {
throw new AnalysisException(
"Cannot resolve DECIMAL precision and scale from NULL type.");
}
Preconditions.checkState(result.isDecimal() && !result.isWildcardDecimal());
}
return result;
}
/**
* Returns true if e is a CastExpr and the target type is a decimal.
*/
private boolean isExplicitCastToDecimal(Expr e) {
if (!(e instanceof CastExpr)) return false;
CastExpr c = (CastExpr)e;
return !c.isImplicit() && c.getType().isDecimal();
}
/**
* Returns a clone of child with all NumericLiterals in it explicitly
* cast to targetType.
*/
private Expr convertNumericLiteralsToFloat(Analyzer analyzer, Expr child,
Type targetType) throws AnalysisException {
if (!targetType.isFloatingPointType() && !targetType.isIntegerType()) return child;
if (targetType.isIntegerType()) targetType = Type.DOUBLE;
List<NumericLiteral> literals = Lists.newArrayList();
child.collectAll(Predicates.instanceOf(NumericLiteral.class), literals);
ExprSubstitutionMap smap = new ExprSubstitutionMap();
for (NumericLiteral l: literals) {
NumericLiteral castLiteral = (NumericLiteral) l.clone();
castLiteral.explicitlyCastToFloat(targetType);
smap.put(l, castLiteral);
}
return child.substitute(smap, analyzer);
}
/**
* Converts numeric literal in the expr tree rooted at this expr to return floating
* point types instead of decimals, if possible.
*
* Decimal has a higher processing cost than floating point and we should not pay
* the cost if the user does not require the accuracy. For example:
* "select float_col + 1.1" would start out with 1.1 as a decimal(2,1) and the
* float_col would be promoted to a high accuracy decimal. This function will identify
* this case and treat 1.1 as a float.
* In the case of "decimal_col + 1.1", 1.1 would remain a decimal.
* In the case of "float_col + cast(1.1 as decimal(2,1))", the result would be a
* decimal.
*
* Another way to think about it is that DecimalLiterals are analyzed as returning
* decimals (of the narrowest precision/scale) and we later convert them to a floating
* point type when it is consistent with the user's intent.
*
* TODO: another option is to do constant folding in the FE and then apply this rule.
*/
protected void convertNumericLiteralsFromDecimal(Analyzer analyzer)
throws AnalysisException {
Preconditions.checkState(this instanceof ArithmeticExpr ||
this instanceof BinaryPredicate);
Preconditions.checkState(children_.size() == 2);
Type t0 = getChild(0).getType();
Type t1 = getChild(1).getType();
boolean c0IsConstantDecimal = getChild(0).isConstant() && t0.isDecimal();
boolean c1IsConstantDecimal = getChild(1).isConstant() && t1.isDecimal();
if (c0IsConstantDecimal && c1IsConstantDecimal) return;
if (!c0IsConstantDecimal && !c1IsConstantDecimal) return;
// Only child(0) or child(1) is a const decimal. See if we can cast it to
// the type of the other child.
if (c0IsConstantDecimal && !isExplicitCastToDecimal(getChild(0))) {
Expr c0 = convertNumericLiteralsToFloat(analyzer, getChild(0), t1);
setChild(0, c0);
}
if (c1IsConstantDecimal && !isExplicitCastToDecimal(getChild(1))) {
Expr c1 = convertNumericLiteralsToFloat(analyzer, getChild(1), t0);
setChild(1, c1);
}
}
/**
* Helper function: analyze list of exprs
*/
public static void analyze(List<? extends Expr> exprs, Analyzer analyzer)
throws AnalysisException {
if (exprs == null) return;
for (Expr expr: exprs) {
expr.analyze(analyzer);
}
}
@Override
public String toSql() {
return (printSqlInParens_) ? "(" + toSqlImpl() + ")" : toSqlImpl();
}
/**
* Returns a SQL string representing this expr. Subclasses should override this method
* instead of toSql() to ensure that parenthesis are properly added around the toSql().
*/
protected abstract String toSqlImpl();
// Convert this expr, including all children, to its Thrift representation.
public TExpr treeToThrift() {
if (type_.isNull()) {
// Hack to ensure BE never sees TYPE_NULL. If an expr makes it this far without
// being cast to a non-NULL type, the type doesn't matter and we can cast it
// arbitrarily.
Preconditions.checkState(this instanceof NullLiteral || this instanceof SlotRef);
return NullLiteral.create(ScalarType.BOOLEAN).treeToThrift();
}
TExpr result = new TExpr();
treeToThriftHelper(result);
return result;
}
// Append a flattened version of this expr, including all children, to 'container'.
protected void treeToThriftHelper(TExpr container) {
Preconditions.checkState(isAnalyzed_,
"Must be analyzed before serializing to thrift. %s", this);
Preconditions.checkState(!type_.isWildcardDecimal());
// The BE should never see TYPE_NULL
Preconditions.checkState(!type_.isNull(), "Expr has type null!");
TExprNode msg = new TExprNode();
msg.type = type_.toThrift();
msg.num_children = children_.size();
if (fn_ != null) {
msg.setFn(fn_.toThrift());
if (fn_.hasVarArgs()) msg.setVararg_start_idx(fn_.getNumArgs() - 1);
}
toThrift(msg);
container.addToNodes(msg);
for (Expr child: children_) {
child.treeToThriftHelper(container);
}
}
// Convert this expr into msg (excluding children), which requires setting
// msg.op as well as the expr-specific field.
protected abstract void toThrift(TExprNode msg);
/**
* Returns the product of the given exprs' number of distinct values or -1 if any of
* the exprs have an invalid number of distinct values.
*/
public static long getNumDistinctValues(List<Expr> exprs) {
if (exprs == null || exprs.isEmpty()) return 0;
long numDistinctValues = 1;
for (Expr expr: exprs) {
if (expr.getNumDistinctValues() == -1) {
numDistinctValues = -1;
break;
}
numDistinctValues *= expr.getNumDistinctValues();
}
return numDistinctValues;
}
public static List<TExpr> treesToThrift(List<? extends Expr> exprs) {
List<TExpr> result = Lists.newArrayList();
for (Expr expr: exprs) {
result.add(expr.treeToThrift());
}
return result;
}
public static com.google.common.base.Predicate<Expr> isAggregatePredicate() {
return isAggregatePredicate_;
}
public boolean isAggregate() {
return isAggregatePredicate_.apply(this);
}
public List<String> childrenToSql() {
List<String> result = Lists.newArrayList();
for (Expr child: children_) {
result.add(child.toSql());
}
return result;
}
public String debugString() {
return (id_ != null ? "exprid=" + id_.toString() + " " : "") + debugString(children_);
}
public static String debugString(List<? extends Expr> exprs) {
if (exprs == null || exprs.isEmpty()) return "";
List<String> strings = Lists.newArrayList();
for (Expr expr: exprs) {
strings.add(expr.debugString());
}
return Joiner.on(" ").join(strings);
}
public static String toSql(List<? extends Expr> exprs) {
if (exprs == null || exprs.isEmpty()) return "";
List<String> strings = Lists.newArrayList();
for (Expr expr: exprs) {
strings.add(expr.toSql());
}
return Joiner.on(", ").join(strings);
}
/**
* Returns true if two expressions are equal. The equality comparison works on analyzed
* as well as unanalyzed exprs by ignoring implicit casts (see CastExpr.equals()).
*/
@Override
public boolean equals(Object obj) {
if (obj == null) return false;
if (obj.getClass() != this.getClass()) return false;
// don't compare type, this could be called pre-analysis
Expr expr = (Expr) obj;
if (children_.size() != expr.children_.size()) return false;
for (int i = 0; i < children_.size(); ++i) {
if (!children_.get(i).equals(expr.children_.get(i))) return false;
}
if (fn_ == null && expr.fn_ == null) return true;
if (fn_ == null || expr.fn_ == null) return false; // One null, one not
// Both fn_'s are not null
return fn_.equals(expr.fn_);
}
/**
* Return true if l1[i].equals(l2[i]) for all i.
*/
public static <C extends Expr> boolean equalLists(List<C> l1, List<C> l2) {
if (l1.size() != l2.size()) return false;
Iterator<C> l1Iter = l1.iterator();
Iterator<C> l2Iter = l2.iterator();
while (l1Iter.hasNext()) {
if (!l1Iter.next().equals(l2Iter.next())) return false;
}
return true;
}
/**
* Return true if l1 equals l2 when both lists are interpreted as sets.
* TODO: come up with something better than O(n^2)?
*/
public static <C extends Expr> boolean equalSets(List<C> l1, List<C> l2) {
if (l1.size() != l2.size()) return false;
return l1.containsAll(l2) && l2.containsAll(l1);
}
/**
* Return true if l1 is a subset of l2.
*/
public static <C extends Expr> boolean isSubset(List<C> l1, List<C> l2) {
if (l1.size() > l2.size()) return false;
return l2.containsAll(l1);
}
/**
* Return the intersection of l1 and l2.599
*/
public static <C extends Expr> List<C> intersect(List<C> l1, List<C> l2) {
List<C> result = new ArrayList<C>();
for (C element: l1) {
if (l2.contains(element)) result.add(element);
}
return result;
}
/**
* Compute the intersection of l1 and l2, given the smap, and
* return the intersecting l1 elements in i1 and the intersecting l2 elements in i2.
*/
public static void intersect(Analyzer analyzer,
List<Expr> l1, List<Expr> l2, ExprSubstitutionMap smap,
List<Expr> i1, List<Expr> i2) {
i1.clear();
i2.clear();
List<Expr> s1List = Expr.substituteList(l1, smap, analyzer);
Preconditions.checkState(s1List.size() == l1.size());
List<Expr> s2List = Expr.substituteList(l2, smap, analyzer);
Preconditions.checkState(s2List.size() == l2.size());
for (int i = 0; i < s1List.size(); ++i) {
Expr s1 = s1List.get(i);
for (int j = 0; j < s2List.size(); ++j) {
Expr s2 = s2List.get(j);
if (s1.equals(s2)) {
i1.add(l1.get(i));
i2.add(l2.get(j));
break;
}
}
}
}
@Override
public int hashCode() {
if (id_ == null) {
throw new UnsupportedOperationException("Expr.hashCode() is not implemented");
} else {
return id_.asInt();
}
}
/**
* Gather conjuncts from this expr and return them in a list.
* A conjunct is an expr that returns a boolean, e.g., Predicates, function calls,
* SlotRefs, etc. Hence, this method is placed here and not in Predicate.
*/
public List<Expr> getConjuncts() {
List<Expr> list = Lists.newArrayList();
if (this instanceof CompoundPredicate
&& ((CompoundPredicate) this).getOp() == CompoundPredicate.Operator.AND) {
// TODO: we have to convert CompoundPredicate.AND to two expr trees for
// conjuncts because NULLs are handled differently for CompoundPredicate.AND
// and conjunct evaluation. This is not optimal for jitted exprs because it
// will result in two functions instead of one. Create a new CompoundPredicate
// Operator (i.e. CONJUNCT_AND) with the right NULL semantics and use that
// instead
list.addAll((getChild(0)).getConjuncts());
list.addAll((getChild(1)).getConjuncts());
} else {
list.add(this);
}
return list;
}
/**
* Returns an analyzed clone of 'this' with exprs substituted according to smap.
* Removes implicit casts and analysis state while cloning/substituting exprs within
* this tree, such that the returned result has minimal implicit casts and types.
* Throws if analyzing the post-substitution expr tree failed.
* If smap is null, this function is equivalent to clone().
*/
public Expr trySubstitute(ExprSubstitutionMap smap, Analyzer analyzer)
throws AnalysisException {
Expr result = clone();
// Return clone to avoid removing casts.
if (smap == null) return result;
result = result.substituteImpl(smap, analyzer);
result.analyze(analyzer);
return result;
}
/**
* Returns an analyzed clone of 'this' with exprs substituted according to smap.
* Removes implicit casts and analysis state while cloning/substituting exprs within
* this tree, such that the returned result has minimal implicit casts and types.
* Expects the analysis of the post-substitution expr to succeed.
* If smap is null, this function is equivalent to clone().
*/
public Expr substitute(ExprSubstitutionMap smap, Analyzer analyzer) {
try {
return trySubstitute(smap, analyzer);
} catch (Exception e) {
throw new IllegalStateException("Failed analysis after expr substitution.", e);
}
}
public static ArrayList<Expr> trySubstituteList(Iterable<? extends Expr> exprs,
ExprSubstitutionMap smap, Analyzer analyzer)
throws AnalysisException {
if (exprs == null) return null;
ArrayList<Expr> result = new ArrayList<Expr>();
for (Expr e: exprs) {
result.add(e.trySubstitute(smap, analyzer));
}
return result;
}
public static ArrayList<Expr> substituteList(Iterable<? extends Expr> exprs,
ExprSubstitutionMap smap, Analyzer analyzer) {
try {
return trySubstituteList(exprs, smap, analyzer);
} catch (Exception e) {
throw new IllegalStateException("Failed analysis after expr substitution.", e);
}
}
/**
* Recursive method that performs the actual substitution for try/substitute() while
* removing implicit casts. Resets the analysis state in all non-SlotRef expressions.
* Exprs that have non-child exprs which should be affected by substitutions must
* override this method and apply the substitution to such exprs as well.
*/
protected Expr substituteImpl(ExprSubstitutionMap smap, Analyzer analyzer)
throws AnalysisException {
if (isImplicitCast()) return getChild(0).substituteImpl(smap, analyzer);
if (smap != null) {
Expr substExpr = smap.get(this);
if (substExpr != null) return substExpr.clone();
}
for (int i = 0; i < children_.size(); ++i) {
children_.set(i, children_.get(i).substituteImpl(smap, analyzer));
}
// SlotRefs must remain analyzed to support substitution across query blocks. All
// other exprs must be analyzed again after the substitution to add implicit casts
// and for resolving their correct function signature.
if (!(this instanceof SlotRef)) resetAnalysisState();
return this;
}
/**
* Resets the internal state of this expr produced by analyze().
* Only modifies this expr, and not its child exprs.
*/
protected void resetAnalysisState() { isAnalyzed_ = false; }
/**
* Resets the internal analysis state of this expr tree. Removes implicit casts.
*/
public Expr reset() {
if (isImplicitCast()) return getChild(0).reset();
for (int i = 0; i < children_.size(); ++i) {
children_.set(i, children_.get(i).reset());
}
resetAnalysisState();
return this;
}
public static ArrayList<Expr> resetList(ArrayList<Expr> l) {
for (int i = 0; i < l.size(); ++i) {
l.set(i, l.get(i).reset());
}
return l;
}
/**
* Creates a deep copy of this expr including its analysis state. The method is
* abstract in this class to force new Exprs to implement it.
*/
@Override
public abstract Expr clone();
/**
* Create a deep copy of 'l'. The elements of the returned list are of the same
* type as the input list.
*/
public static <C extends Expr> ArrayList<C> cloneList(Iterable<C> l) {
Preconditions.checkNotNull(l);
ArrayList<C> result = new ArrayList<C>();
for (Expr element: l) {
result.add((C) element.clone());
}
return result;
}
/**
* Removes duplicate exprs (according to equals()).
*/
public static <C extends Expr> void removeDuplicates(List<C> l) {
if (l == null) return;
ListIterator<C> it1 = l.listIterator();
while (it1.hasNext()) {
C e1 = it1.next();
ListIterator<C> it2 = l.listIterator();
boolean duplicate = false;
while (it2.hasNext()) {
C e2 = it2.next();
// only check up to but excluding e1
if (e1 == e2) break;
if (e1.equals(e2)) {
duplicate = true;
break;
}
}
if (duplicate) it1.remove();
}
}
/**
* Removes constant exprs
*/
public static <C extends Expr> void removeConstants(List<C> l) {
if (l == null) return;
ListIterator<C> it = l.listIterator();
while (it.hasNext()) {
C e = it.next();
if (e.isConstant()) it.remove();
}
}
/**
* Returns true if expr is fully bound by tid, otherwise false.
*/
public boolean isBound(TupleId tid) {
return isBoundByTupleIds(Lists.newArrayList(tid));
}
/**
* Returns true if expr is fully bound by tids, otherwise false.
*/
public boolean isBoundByTupleIds(List<TupleId> tids) {
for (Expr child: children_) {
if (!child.isBoundByTupleIds(tids)) return false;
}
return true;
}
/**
* Returns true if expr is fully bound by slotId, otherwise false.
*/
public boolean isBound(SlotId slotId) {
return isBoundBySlotIds(Lists.newArrayList(slotId));
}
/**
* Returns true if expr is fully bound by slotIds, otherwise false.
*/
public boolean isBoundBySlotIds(List<SlotId> slotIds) {
for (Expr child: children_) {
if (!child.isBoundBySlotIds(slotIds)) return false;
}
return true;
}
public static boolean isBound(List<? extends Expr> exprs, List<TupleId> tids) {
for (Expr expr: exprs) {
if (!expr.isBoundByTupleIds(tids)) return false;
}
return true;
}
public void getIds(List<TupleId> tupleIds, List<SlotId> slotIds) {
Set<TupleId> tupleIdSet = Sets.newHashSet();
Set<SlotId> slotIdSet = Sets.newHashSet();
getIdsHelper(tupleIdSet, slotIdSet);
if (tupleIds != null) tupleIds.addAll(tupleIdSet);
if (slotIds != null) slotIds.addAll(slotIdSet);
}
protected void getIdsHelper(Set<TupleId> tupleIds, Set<SlotId> slotIds) {
for (Expr child: children_) {
child.getIdsHelper(tupleIds, slotIds);
}
}
public static <C extends Expr> void getIds(List<? extends Expr> exprs,
List<TupleId> tupleIds, List<SlotId> slotIds) {
if (exprs == null) return;
for (Expr e: exprs) {
e.getIds(tupleIds, slotIds);
}
}
/**
* @return true if this is an instance of LiteralExpr
*/
public boolean isLiteral() {
return this instanceof LiteralExpr;
}
/**
* @return true if this expr can be evaluated with Expr::GetValue(NULL),
* ie, if it doesn't contain any references to runtime variables (which
* at the moment are only slotrefs and subqueries).
*/
public boolean isConstant() {
return !contains(Predicates.instanceOf(SlotRef.class)) &&
!contains(Predicates.instanceOf(Subquery.class));
}
/**
* @return true if this expr is either a null literal or a cast from
* a null literal.
*/
public boolean isNullLiteral() {
if (this instanceof NullLiteral) return true;
if (!(this instanceof CastExpr)) return false;
Preconditions.checkState(children_.size() == 1);
return children_.get(0).isNullLiteral();
}
/**
* Return true if this expr is a scalar subquery.
*/
public boolean isScalarSubquery() {
Preconditions.checkState(isAnalyzed_);
return this instanceof Subquery && getType().isScalarType();
}
/**
* Checks whether this expr returns a boolean type or NULL type.
* If not, throws an AnalysisException with an appropriate error message using
* 'name' as a prefix. For example, 'name' could be "WHERE clause".
* The error message only contains this.toSql() if printExpr is true.
*/
public void checkReturnsBool(String name, boolean printExpr) throws AnalysisException {
if (!type_.isBoolean() && !type_.isNull()) {
throw new AnalysisException(
String.format("%s%s requires return type 'BOOLEAN'. " +
"Actual type is '%s'.", name, (printExpr) ? " '" + toSql() + "'" : "",
type_.toString()));
}
}
/**
* Checks validity of cast, and
* calls uncheckedCastTo() to
* create a cast expression that casts
* this to a specific type.
* @param targetType
* type to be cast to
* @return cast expression, or converted literal,
* should never return null
* @throws AnalysisException
* when an invalid cast is asked for, for example,
* failure to convert a string literal to a date literal
*/
public final Expr castTo(Type targetType) throws AnalysisException {
Type type = Type.getAssignmentCompatibleType(this.type_, targetType);
Preconditions.checkState(type.isValid(), "cast %s to %s", this.type_, targetType);
// If the targetType is NULL_TYPE then ignore the cast because NULL_TYPE
// is compatible with all types and no cast is necessary.
if (targetType.isNull()) return this;
if (!targetType.isDecimal()) {
// requested cast must be to assignment-compatible type
// (which implies no loss of precision)
Preconditions.checkArgument(targetType.equals(type),
"targetType=" + targetType + " type=" + type);
}
return uncheckedCastTo(targetType);
}
/**
* Create an expression equivalent to 'this' but returning targetType;
* possibly by inserting an implicit cast,
* or by returning an altogether new expression
* or by returning 'this' with a modified return type'.
* @param targetType
* type to be cast to
* @return cast expression, or converted literal,
* should never return null
* @throws AnalysisException
* when an invalid cast is asked for, for example,
* failure to convert a string literal to a date literal
*/
protected Expr uncheckedCastTo(Type targetType) throws AnalysisException {
return new CastExpr(targetType, this, true);
}
/**
* Add a cast expression above child.
* If child is a literal expression, we attempt to
* convert the value of the child directly, and not insert a cast node.
* @param targetType
* type to be cast to
* @param childIndex
* index of child to be cast
*/
public void castChild(Type targetType, int childIndex) throws AnalysisException {
Expr child = getChild(childIndex);
Expr newChild = child.castTo(targetType);
setChild(childIndex, newChild);
}
/**
* Convert child to to targetType, possibly by inserting an implicit cast, or by
* returning an altogether new expression, or by returning 'this' with a modified
* return type'.