source: branches/blt4/packages/vizservers/nanovis/CmdProc.cpp @ 1642

#include <tcl.h>
#include "CmdProc.h"
#include <string.h>

/*
 *-------------------------------------------------------------------------------
 *
 * BinaryOpSearch --
 *
 *      Performs a binary search on the array of command operation
 *      specifications to find a partial, anchored match for the given
 *      operation string.
 *
 * Results:
 *  If the string matches unambiguously the index of the specification in
 *  the array is returned.  If the string does not match, even as an
 *  abbreviation, any operation, -1 is returned.  If the string matches,
 *  but ambiguously -2 is returned.
 *
 *-------------------------------------------------------------------------------
 */
static int
BinaryOpSearch(
    Rappture::CmdSpec *specs, 
    int nSpecs, 
    char *string)       /* Name of minor operation to search for */
{
    char c;
    int high, low;
    size_t length;

    low = 0;
    high = nSpecs - 1;
    c = string[0];
    length = strlen(string);
    while (low <= high) {
    Rappture::CmdSpec *specPtr;
    int compare;
    int median;
    
    median = (low + high) >> 1;
    specPtr = specs + median;

    /* Test the first character */
    compare = c - specPtr->name[0];
    if (compare == 0) {
        /* Now test the entire string */
        compare = strncmp(string, specPtr->name, length);
        if (compare == 0) {
        if ((int)length < specPtr->minChars) {
            return -2;  /* Ambiguous operation name */
        }
        }
    }
    if (compare < 0) {
        high = median - 1;
    } else if (compare > 0) {
        low = median + 1;
    } else {
        return median;  /* Op found. */
    }
    }
    return -1;          /* Can't find operation */
}


/*
 *-------------------------------------------------------------------------------
 *
 * LinearOpSearch --
 *
 *      Performs a binary search on the array of command operation
 *      specifications to find a partial, anchored match for the given
 *      operation string.
 *
 * Results:
 *  If the string matches unambiguously the index of the specification in
 *  the array is returned.  If the string does not match, even as an
 *  abbreviation, any operation, -1 is returned.  If the string matches,
 *  but ambiguously -2 is returned.
 *
 *-------------------------------------------------------------------------------
 */
static int
LinearOpSearch(
    Rappture::CmdSpec *specs,
    int nSpecs,
    char *string)       /* Name of minor operation to search for */
{
    Rappture::CmdSpec *specPtr;
    char c;
    size_t length;
    int nMatches, last;
    int i;

    c = string[0];
    length = strlen(string);
    nMatches = 0;
    last = -1;
    for (specPtr = specs, i = 0; i < nSpecs; i++, specPtr++) {
    if ((c == specPtr->name[0]) && 
        (strncmp(string, specPtr->name, length) == 0)) {
        last = i;
        nMatches++;
        if ((int)length == specPtr->minChars) {
        break;
        }
    }
    }
    if (nMatches > 1) {
    return -2;      /* Ambiguous operation name */
    } 
    if (nMatches == 0) {
    return -1;      /* Can't find operation */
    } 
    return last;        /* Op found. */
}

/*
 *-------------------------------------------------------------------------------
 *
 * GetOpFromObj --
 *
 *      Find the command operation given a string name.  This is useful where
 *      a group of command operations have the same argument signature.
 *
 * Results:
 *      If found, a pointer to the procedure (function pointer) is returned.
 *      Otherwise NULL is returned and an error message containing a list of
 *      the possible commands is returned in interp->result.
 *
 *-------------------------------------------------------------------------------
 */
Tcl_ObjCmdProc *
Rappture::GetOpFromObj(
    Tcl_Interp *interp,                 /* Interpreter to report errors to */
    int nSpecs,                         /* Number of specifications in array */
    CmdSpec *specs,                     /* Op specification array */
    int operPos,                        /* Position of operation in argument
                                         * list. */
    int objc,                           /* Number of arguments in the argument
                                         * vector.  This includes any prefixed
                                         * arguments */ 
    Tcl_Obj *CONST *objv,               /* Argument vector */
    int flags)
{
    CmdSpec *specPtr;
    char *string;
    int n;

    if (objc <= operPos) {  /* No operation argument */
    Tcl_AppendResult(interp, "wrong # args: ", (char *)NULL);
      usage:
    Tcl_AppendResult(interp, "should be one of...", (char *)NULL);
    for (n = 0; n < nSpecs; n++) {
        int i;

        Tcl_AppendResult(interp, "\n  ", (char *)NULL);
        for (i = 0; i < operPos; i++) {
        Tcl_AppendResult(interp, Tcl_GetString(objv[i]), " ", 
             (char *)NULL);
        }
        specPtr = specs + n;
        Tcl_AppendResult(interp, specPtr->name, " ", specPtr->usage,
        (char *)NULL);
    }
    return NULL;
    }
    string = Tcl_GetString(objv[operPos]);
    if (flags & CMDSPEC_LINEAR_SEARCH) {
    n = LinearOpSearch(specs, nSpecs, string);
    } else {
    n = BinaryOpSearch(specs, nSpecs, string);
    }
    if (n == -2) {
    char c;
    size_t length;

    Tcl_AppendResult(interp, "ambiguous", (char *)NULL);
    if (operPos > 2) {
        Tcl_AppendResult(interp, " ", Tcl_GetString(objv[operPos - 1]), 
        (char *)NULL);
    }
    Tcl_AppendResult(interp, " operation \"", string, "\" matches: ",
        (char *)NULL);

    c = string[0];
    length = strlen(string);
    for (n = 0; n < nSpecs; n++) {
        specPtr = specs + n;
        if ((c == specPtr->name[0]) &&
        (strncmp(string, specPtr->name, length) == 0)) {
        Tcl_AppendResult(interp, " ", specPtr->name, (char *)NULL);
        }
    }
    return NULL;

    } else if (n == -1) {   /* Can't find operation, display help */
    Tcl_AppendResult(interp, "bad", (char *)NULL);
    if (operPos > 2) {
        Tcl_AppendResult(interp, " ", Tcl_GetString(objv[operPos - 1]), 
        (char *)NULL);
    }
    Tcl_AppendResult(interp, " operation \"", string, "\": ", (char *)NULL);
    goto usage;
    }
    specPtr = specs + n;
    if ((objc < specPtr->minArgs) || 
    ((specPtr->maxArgs > 0) && (objc > specPtr->maxArgs))) {
    int i;

    Tcl_AppendResult(interp, "wrong # args: should be \"", (char *)NULL);
    for (i = 0; i < operPos; i++) {
        Tcl_AppendResult(interp, Tcl_GetString(objv[i]), " ", 
        (char *)NULL);
    }
    Tcl_AppendResult(interp, specPtr->name, " ", specPtr->usage, "\"",
        (char *)NULL);
    return NULL;
    }
    return specPtr->proc;
}