Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 444 insertions, 0 deletions

diff --git a/src/backend/utils/adt/tsquery_cleanup.c b/src/backend/utils/adt/tsquery_cleanup.c
new file mode 100644
index 0000000..82ae284
--- /dev/null
+++ b/src/backend/utils/adt/tsquery_cleanup.c
@@ -0,0 +1,444 @@
+/*-------------------------------------------------------------------------
+ *
+ * tsquery_cleanup.c
+ *	 Cleanup query from NOT values and/or stopword
+ *	 Utility functions to correct work.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/adt/tsquery_cleanup.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "miscadmin.h"
+#include "tsearch/ts_utils.h"
+
+typedef struct NODE
+{
+	struct NODE *left;
+	struct NODE *right;
+	QueryItem  *valnode;
+} NODE;
+
+/*
+ * make query tree from plain view of query
+ */
+static NODE *
+maketree(QueryItem *in)
+{
+	NODE	   *node = (NODE *) palloc(sizeof(NODE));
+
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
+	node->valnode = in;
+	node->right = node->left = NULL;
+	if (in->type == QI_OPR)
+	{
+		node->right = maketree(in + 1);
+		if (in->qoperator.oper != OP_NOT)
+			node->left = maketree(in + in->qoperator.left);
+	}
+	return node;
+}
+
+/*
+ * Internal state for plaintree and plainnode
+ */
+typedef struct
+{
+	QueryItem  *ptr;
+	int			len;			/* allocated size of ptr */
+	int			cur;			/* number of elements in ptr */
+} PLAINTREE;
+
+static void
+plainnode(PLAINTREE *state, NODE *node)
+{
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
+	if (state->cur == state->len)
+	{
+		state->len *= 2;
+		state->ptr = (QueryItem *) repalloc((void *) state->ptr, state->len * sizeof(QueryItem));
+	}
+	memcpy((void *) &(state->ptr[state->cur]), (void *) node->valnode, sizeof(QueryItem));
+	if (node->valnode->type == QI_VAL)
+		state->cur++;
+	else if (node->valnode->qoperator.oper == OP_NOT)
+	{
+		state->ptr[state->cur].qoperator.left = 1;
+		state->cur++;
+		plainnode(state, node->right);
+	}
+	else
+	{
+		int			cur = state->cur;
+
+		state->cur++;
+		plainnode(state, node->right);
+		state->ptr[cur].qoperator.left = state->cur - cur;
+		plainnode(state, node->left);
+	}
+	pfree(node);
+}
+
+/*
+ * make plain view of tree from a NODE-tree representation
+ */
+static QueryItem *
+plaintree(NODE *root, int *len)
+{
+	PLAINTREE	pl;
+
+	pl.cur = 0;
+	pl.len = 16;
+	if (root && (root->valnode->type == QI_VAL || root->valnode->type == QI_OPR))
+	{
+		pl.ptr = (QueryItem *) palloc(pl.len * sizeof(QueryItem));
+		plainnode(&pl, root);
+	}
+	else
+		pl.ptr = NULL;
+	*len = pl.cur;
+	return pl.ptr;
+}
+
+static void
+freetree(NODE *node)
+{
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
+	if (!node)
+		return;
+	if (node->left)
+		freetree(node->left);
+	if (node->right)
+		freetree(node->right);
+	pfree(node);
+}
+
+/*
+ * clean tree for ! operator.
+ * It's useful for debug, but in
+ * other case, such view is used with search in index.
+ * Operator ! always return TRUE
+ */
+static NODE *
+clean_NOT_intree(NODE *node)
+{
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
+	if (node->valnode->type == QI_VAL)
+		return node;
+
+	if (node->valnode->qoperator.oper == OP_NOT)
+	{
+		freetree(node);
+		return NULL;
+	}
+
+	/* operator & or | */
+	if (node->valnode->qoperator.oper == OP_OR)
+	{
+		if ((node->left = clean_NOT_intree(node->left)) == NULL ||
+			(node->right = clean_NOT_intree(node->right)) == NULL)
+		{
+			freetree(node);
+			return NULL;
+		}
+	}
+	else
+	{
+		NODE	   *res = node;
+
+		Assert(node->valnode->qoperator.oper == OP_AND ||
+			   node->valnode->qoperator.oper == OP_PHRASE);
+
+		node->left = clean_NOT_intree(node->left);
+		node->right = clean_NOT_intree(node->right);
+		if (node->left == NULL && node->right == NULL)
+		{
+			pfree(node);
+			res = NULL;
+		}
+		else if (node->left == NULL)
+		{
+			res = node->right;
+			pfree(node);
+		}
+		else if (node->right == NULL)
+		{
+			res = node->left;
+			pfree(node);
+		}
+		return res;
+	}
+	return node;
+}
+
+QueryItem *
+clean_NOT(QueryItem *ptr, int *len)
+{
+	NODE	   *root = maketree(ptr);
+
+	return plaintree(clean_NOT_intree(root), len);
+}
+
+
+/*
+ * Remove QI_VALSTOP (stopword) nodes from query tree.
+ *
+ * Returns NULL if the query degenerates to nothing.  Input must not be NULL.
+ *
+ * When we remove a phrase operator due to removing one or both of its
+ * arguments, we might need to adjust the distance of a parent phrase
+ * operator.  For example, 'a' is a stopword, so:
+ *		(b <-> a) <-> c  should become	b <2> c
+ *		b <-> (a <-> c)  should become	b <2> c
+ *		(b <-> (a <-> a)) <-> c  should become	b <3> c
+ *		b <-> ((a <-> a) <-> c)  should become	b <3> c
+ * To handle that, we define two output parameters:
+ *		ladd: amount to add to a phrase distance to the left of this node
+ *		radd: amount to add to a phrase distance to the right of this node
+ * We need two outputs because we could need to bubble up adjustments to two
+ * different parent phrase operators.  Consider
+ *		w <-> (((a <-> x) <2> (y <3> a)) <-> z)
+ * After we've removed the two a's and are considering the <2> node (which is
+ * now just x <2> y), we have an ladd distance of 1 that needs to propagate
+ * up to the topmost (leftmost) <->, and an radd distance of 3 that needs to
+ * propagate to the rightmost <->, so that we'll end up with
+ *		w <2> ((x <2> y) <4> z)
+ * Near the bottom of the tree, we may have subtrees consisting only of
+ * stopwords.  The distances of any phrase operators within such a subtree are
+ * summed and propagated to both ladd and radd, since we don't know which side
+ * of the lowest surviving phrase operator we are in.  The rule is that any
+ * subtree that degenerates to NULL must return equal values of ladd and radd,
+ * and the parent node dealing with it should incorporate only one of those.
+ *
+ * Currently, we only implement this adjustment for adjacent phrase operators.
+ * Thus for example 'x <-> ((a <-> y) | z)' will become 'x <-> (y | z)', which
+ * isn't ideal, but there is no way to represent the really desired semantics
+ * without some redesign of the tsquery structure.  Certainly it would not be
+ * any better to convert that to 'x <2> (y | z)'.  Since this is such a weird
+ * corner case, let it go for now.  But we can fix it in cases where the
+ * intervening non-phrase operator also gets removed, for example
+ * '((x <-> a) | a) <-> y' will become 'x <2> y'.
+ */
+static NODE *
+clean_stopword_intree(NODE *node, int *ladd, int *radd)
+{
+	/* since this function recurses, it could be driven to stack overflow. */
+	check_stack_depth();
+
+	/* default output parameters indicate no change in parent distance */
+	*ladd = *radd = 0;
+
+	if (node->valnode->type == QI_VAL)
+		return node;
+	else if (node->valnode->type == QI_VALSTOP)
+	{
+		pfree(node);
+		return NULL;
+	}
+
+	Assert(node->valnode->type == QI_OPR);
+
+	if (node->valnode->qoperator.oper == OP_NOT)
+	{
+		/* NOT doesn't change pattern width, so just report child distances */
+		node->right = clean_stopword_intree(node->right, ladd, radd);
+		if (!node->right)
+		{
+			freetree(node);
+			return NULL;
+		}
+	}
+	else
+	{
+		NODE	   *res = node;
+		bool		isphrase;
+		int			ndistance,
+					lladd,
+					lradd,
+					rladd,
+					rradd;
+
+		/* First, recurse */
+		node->left = clean_stopword_intree(node->left, &lladd, &lradd);
+		node->right = clean_stopword_intree(node->right, &rladd, &rradd);
+
+		/* Check if current node is OP_PHRASE, get its distance */
+		isphrase = (node->valnode->qoperator.oper == OP_PHRASE);
+		ndistance = isphrase ? node->valnode->qoperator.distance : 0;
+
+		if (node->left == NULL && node->right == NULL)
+		{
+			/*
+			 * When we collapse out a phrase node entirely, propagate its own
+			 * distance into both *ladd and *radd; it is the responsibility of
+			 * the parent node to count it only once.  Also, for a phrase
+			 * node, distances coming from children are summed and propagated
+			 * up to parent (we assume lladd == lradd and rladd == rradd, else
+			 * rule was broken at a lower level).  But if this isn't a phrase
+			 * node, take the larger of the two child distances; that
+			 * corresponds to what TS_execute will do in non-stopword cases.
+			 */
+			if (isphrase)
+				*ladd = *radd = lladd + ndistance + rladd;
+			else
+				*ladd = *radd = Max(lladd, rladd);
+			freetree(node);
+			return NULL;
+		}
+		else if (node->left == NULL)
+		{
+			/* Removing this operator and left subnode */
+			/* lladd and lradd are equal/redundant, don't count both */
+			if (isphrase)
+			{
+				/* operator's own distance must propagate to left */
+				*ladd = lladd + ndistance + rladd;
+				*radd = rradd;
+			}
+			else
+			{
+				/* at non-phrase op, just forget the left subnode entirely */
+				*ladd = rladd;
+				*radd = rradd;
+			}
+			res = node->right;
+			pfree(node);
+		}
+		else if (node->right == NULL)
+		{
+			/* Removing this operator and right subnode */
+			/* rladd and rradd are equal/redundant, don't count both */
+			if (isphrase)
+			{
+				/* operator's own distance must propagate to right */
+				*ladd = lladd;
+				*radd = lradd + ndistance + rradd;
+			}
+			else
+			{
+				/* at non-phrase op, just forget the right subnode entirely */
+				*ladd = lladd;
+				*radd = lradd;
+			}
+			res = node->left;
+			pfree(node);
+		}
+		else if (isphrase)
+		{
+			/* Absorb appropriate corrections at this level */
+			node->valnode->qoperator.distance += lradd + rladd;
+			/* Propagate up any unaccounted-for corrections */
+			*ladd = lladd;
+			*radd = rradd;
+		}
+		else
+		{
+			/* We're keeping a non-phrase operator, so ladd/radd remain 0 */
+		}
+
+		return res;
+	}
+	return node;
+}
+
+/*
+ * Number of elements in query tree
+ */
+static int32
+calcstrlen(NODE *node)
+{
+	int32		size = 0;
+
+	if (node->valnode->type == QI_VAL)
+	{
+		size = node->valnode->qoperand.length + 1;
+	}
+	else
+	{
+		Assert(node->valnode->type == QI_OPR);
+
+		size = calcstrlen(node->right);
+		if (node->valnode->qoperator.oper != OP_NOT)
+			size += calcstrlen(node->left);
+	}
+
+	return size;
+}
+
+/*
+ * Remove QI_VALSTOP (stopword) nodes from TSQuery.
+ */
+TSQuery
+cleanup_tsquery_stopwords(TSQuery in)
+{
+	int32		len,
+				lenstr,
+				commonlen,
+				i;
+	NODE	   *root;
+	int			ladd,
+				radd;
+	TSQuery		out;
+	QueryItem  *items;
+	char	   *operands;
+
+	if (in->size == 0)
+		return in;
+
+	/* eliminate stop words */
+	root = clean_stopword_intree(maketree(GETQUERY(in)), &ladd, &radd);
+	if (root == NULL)
+	{
+		ereport(NOTICE,
+				(errmsg("text-search query contains only stop words or doesn't contain lexemes, ignored")));
+		out = palloc(HDRSIZETQ);
+		out->size = 0;
+		SET_VARSIZE(out, HDRSIZETQ);
+		return out;
+	}
+
+	/*
+	 * Build TSQuery from plain view
+	 */
+
+	lenstr = calcstrlen(root);
+	items = plaintree(root, &len);
+	commonlen = COMPUTESIZE(len, lenstr);
+
+	out = palloc(commonlen);
+	SET_VARSIZE(out, commonlen);
+	out->size = len;
+
+	memcpy(GETQUERY(out), items, len * sizeof(QueryItem));
+
+	items = GETQUERY(out);
+	operands = GETOPERAND(out);
+	for (i = 0; i < out->size; i++)
+	{
+		QueryOperand *op = (QueryOperand *) &items[i];
+
+		if (op->type != QI_VAL)
+			continue;
+
+		memcpy(operands, GETOPERAND(in) + op->distance, op->length);
+		operands[op->length] = '\0';
+		op->distance = operands - GETOPERAND(out);
+		operands += op->length + 1;
+	}
+
+	return out;
+}