105 lines
4.0 KiB
C
105 lines
4.0 KiB
C
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/*****************************************************************************/
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/* Copyright (C) 2020 NORMAN MEGILL nm at alum.mit.edu */
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/* License terms: GNU General Public License */
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/*****************************************************************************/
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/*34567890123456 (79-character line to adjust editor window) 2345678901234567*/
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#ifndef METAMATH_MMUNIF_H_
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#define METAMATH_MMUNIF_H_
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#include "mmdata.h"
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extern long g_minSubstLen; /* User-settable value - 0 or 1 */
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extern long g_userMaxUnifTrials;
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/* User-defined upper limit (# backtracks) for unification trials */
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extern long g_unifTrialCount;
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/* 0 means don't time out; 1 means start counting trials */
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extern long g_unifTimeouts; /* Number of timeouts so far for this command */
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extern flag g_hentyFilter; /* Turns Henty filter on or off */
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/* 26-Sep-2010 nm */
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extern flag g_bracketMatchInit; /* So eraseSource() (mmcmds.c) can clr it */
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/* 1-Oct-2017 nm Made this global so eraseSource() (mmcmds.c) can clr it */
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extern nmbrString *g_firstConst;
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/* 2-Oct-2017 nm Made these global so eraseSource() (mmcmds.c) can clr them */
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extern nmbrString *g_lastConst;
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extern nmbrString *g_oneConst;
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nmbrString *makeSubstUnif(flag *newVarFlag,
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nmbrString *trialScheme, pntrString *stateVector);
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char unify(
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nmbrString *schemeA,
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nmbrString *schemeB,
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/* nmbrString **unifiedScheme, */ /* stateVector[8] holds this */
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pntrString **stateVector,
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long reEntryFlag);
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/* This function unifies two math token strings, schemeA and
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schemeB. The result is contained in unifiedScheme.
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0 is returned if no assignment is possible.
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If reEntryFlag is 1, the next possible set of assignments, if any,
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is returned. 2 is returned if the unification times out.
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(*stateVector) contains the state of the previous
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call. It is the caller's responsibility to deallocate the
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contents of (*stateVector) when done, UNLESS a 0 is returned.
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The caller must assign (*stateVector) to a legal pntrString
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(e.g. NULL_PNTRSTRING) before calling.
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All variables with a tokenNum > saveMathTokens are assumed
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to be "unknown" variables that can be assigned; all other
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variables are treated like constants in the unification
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algorithm.
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The "unknown" variable assignments are contained in (*stateVector)
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(which is a complex structure, described below). Some "unknown"
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variables may have no assignment, in which case they will
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remain "unknown", and others may have assignments which include
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"unknown" variables.
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*/
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/* oneDirUnif() is like unify(), except that when reEntryFlag is 1,
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a new unification is returned ONLY if the assignments to the
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variables in schemeA have changed. This is used to speed up the
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program. */
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flag oneDirUnif(
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nmbrString *schemeA,
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nmbrString *schemeB,
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pntrString **stateVector,
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long reEntryFlag);
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/* uniqueUnif() is like unify(), but there is no reEntryFlag, and 3 possible
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values are returned:
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0: no unification was possible.
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1: exactly one unification was possible, and stateVector is valid.
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2: unification timed out.
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3: more than one unification was possible. */
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char uniqueUnif(
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nmbrString *schemeA,
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nmbrString *schemeB,
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pntrString **stateVector);
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/* unifyH() is like unify(), except that when reEntryFlag is 1,
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a new unification is returned ONLY if the normalized unification
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does not previously exist in the "Henty filter". This reduces
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ambiguous unifications. The values returned are the same as
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those returned by unify(). (The elimination of equivalent
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unifications was suggested by Jeremy Henty.) */
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char unifyH(
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nmbrString *schemeA,
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nmbrString *schemeB,
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pntrString **stateVector,
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long reEntryFlag);
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/* Cleans out a stateVector if not empty */
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void purgeStateVector(pntrString **stateVector);
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/* Prints the substitutions determined by unify for debugging purposes */
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void printSubst(pntrString *stateVector);
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#endif /* METAMATH_MMUNIF_H_ */
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