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contract.cxx

/* ----------------------------------------------------------------------------- 
 * contract.cxx
 *
 *     Support for Wrap by Contract in SWIG
 * 
 * Author(s) : Songyan Feng (Tiger) (songyanf@cs.uchicago.edu)
 *             David Beazley (beazley@cs.uchicago.edu)
 *
 * Department of Computer Science
 * University of Chicago
 *
 * Copyright (C) 1999-2003.  The University of Chicago
 * See the file LICENSE for information on usage and redistribution.    
 * ----------------------------------------------------------------------------- */

char cvsroot_contract_cxx[] = "/cvsroot/SWIG/Source/Modules/contract.cxx,v 1.13 2003/12/28 21:47:58 cheetah Exp";

#include "swigmod.h"

/* Contract structure.  This holds rules about the different kinds of contract sections
   and their combination rules */

struct contract {
  const char *section;
  const char *combiner;
};
/* Contract rules.  This table defines what contract sections are recognized as well as
   how contracts are to combined via inheritance */

static contract Rules[] = {
  {"require:", "&&"},
  {"ensure:",  "||"},
  { NULL, NULL}
};

/************************************************************************
 * class Contracts:
 *
 * This class defines the functions that need to be used in 
 *         "wrap by contract" module.
 *************************************************************************/

class Contracts : public Dispatcher {
  String *make_expression(String *s, Node *n);
  void    substitute_parms(String *s, ParmList *p, int method);
public:
  Hash *ContractSplit(Node *n);
  int emit_contract(Node *n, int method);
  int cDeclaration(Node *n);
  int constructorDeclaration(Node  *n);
  int externDeclaration(Node *n);
  int extendDirective(Node *n);
  int importDirective(Node *n);
  int includeDirective(Node *n);
  int classDeclaration(Node *n);
  virtual int top(Node *n);
};

static int      Contract_Mode = 0;    /* contract option */
static int      InClass       = 0;    /* Parsing C++ or not */
static int      InConstructor = 0;
static Node    *CurrentClass  = 0;

/* Set the contract mode, default is 0 (not open) */
/* Normally set in main.cxx, when get the "-contracts" option */
void Swig_contract_mode_set(int flag) {
  Contract_Mode = flag;
}
/* Get the contract mode */
int Swig_contract_mode_get() {
  return Contract_Mode;
}

/* Apply contracts */
void Swig_contracts(Node *n) {

  Contracts *a = new Contracts;
  a->top(n);
  delete a;
}

/* Split the whole contract into preassertion, postassertion and others */
Hash *Contracts::ContractSplit(Node *n) {

  String *contract   = Getattr(n, "feature:contract");  
  Hash   *result;
  if (!contract)
    return NULL;

  result = NewHash();
  String *current_section = NewString("");
  const char   *current_section_name = Rules[0].section;
  List *l = SplitLines(contract);

  Iterator i;
  for (i = First(l); i.item; i = Next(i)) {
    int found = 0;
    if (Strstr(i.item,"{")) continue;
    if (Strstr(i.item,"}")) continue;
    for (int j = 0; Rules[j].section; j++) {
      if (Strstr(i.item,Rules[j].section)) {
      if (Len(current_section)) {
        Setattr(result,current_section_name,current_section);
        current_section = Getattr(result,Rules[j].section);
        if (!current_section) current_section = NewString("");
      } 
      current_section_name = Rules[j].section;
      found = 1;
      break;
      }
    }
    if (!found) Append(current_section, i.item);
  }
  if (Len(current_section)) Setattr(result, current_section_name, current_section);
  return result;
}

/* This function looks in base classes and collects contracts found */
void inherit_contracts(Node *c, Node *n, Hash *contracts, Hash *messages) {
  
  Node *b, *temp;
  String *name, *type, *local_decl, *base_decl;
  List   *bases;
  int     found = 0;

  bases = Getattr(c,"bases");
  if (!bases) return;
    
  name = Getattr(n, "name");
  type = Getattr(n, "type");
  local_decl = Getattr(n, "decl");
  if (local_decl) {
    local_decl = SwigType_typedef_resolve_all(local_decl);
  } else {
    return;
  }
  /* Width first search */
  for (int i = 0; i < Len(bases); i++) {
    b = Getitem(bases,i);
    temp = firstChild (b);
    while (temp) {
      base_decl = Getattr(temp, "decl");
      if (base_decl) {
      base_decl = SwigType_typedef_resolve_all(base_decl);
      if ( (checkAttribute(temp, "storage", "virtual")) &&
           (checkAttribute(temp, "name", name)) &&
           (checkAttribute(temp, "type", type)) &&
           (!Strcmp(local_decl, base_decl)) ) {
        /* Yes, match found. */
        Hash *icontracts = Getattr(temp,"contract:rules");
        Hash *imessages = Getattr(temp,"contract:messages");
        found = 1;
        if (icontracts && imessages) {
          /* Add inherited contracts and messages to the contract rules above */
          int j = 0;
          for (j = 0; Rules[j].section; j++) {
            String *t = Getattr(contracts, Rules[j].section);
            String *s = Getattr(icontracts, Rules[j].section);
            if (s) {
            if (t) {
              Insert(t,0,"(");
              Printf(t,") %s (%s)", Rules[j].combiner, s);
              String *m = Getattr(messages, Rules[j].section);
              Printf(m," %s [%s from %s]", Rules[j].combiner, Getattr(imessages,Rules[j].section), Getattr(b,"name"));
            } else {
              Setattr(contracts, Rules[j].section, NewString(s));
              Setattr(messages,Rules[j].section,NewStringf("[%s from %s]", Getattr(imessages,Rules[j].section), Getattr(b,"name")));
            }
            }
          }
        }
      }
      Delete(base_decl);
      }
      temp = nextSibling(temp);
    }
  }
  Delete(local_decl);
  if (!found) {
    for (int j = 0; j < Len(bases); j++) {
      b = Getitem(bases,j);
      inherit_contracts(b,n,contracts,messages);
    }
  }
}

/* This function cleans up the assertion string by removing some extraneous characters.
   Splitting the assertion into pieces */

String *Contracts::make_expression(String *s, Node *n) {
  String   *str_assert, *expr = 0;
  List     *list_assert;

  str_assert = NewString(s);
  /* Omit all useless characters and split by ; */
  Replaceall(str_assert, "\n", "");
  Replaceall(str_assert, "{", "");
  Replaceall(str_assert, "}", "");
  Replace(str_assert, " ", "", DOH_REPLACE_ANY | DOH_REPLACE_NOQUOTE);
  Replace(str_assert, "\t", "", DOH_REPLACE_ANY | DOH_REPLACE_NOQUOTE);

  list_assert = Split(str_assert, ';', -1);
  Delete(str_assert);
  
  /* build up new assertion */
  str_assert = NewString("");
  Iterator ei;

  for (ei = First(list_assert); ei.item; ei = Next(ei)) {
    expr = ei.item;
    if (Len(expr)) {
      Replaceid(expr, Getattr(n,"name"), "result");
      if (Len(str_assert))
      Append(str_assert, "&&");
      Printf(str_assert, "(%s)", expr);
    }
  }
  Delete(list_assert);
  return str_assert;
}

/* This function substitutes parameter names for argument names in the
   contract specification.  Note: it is assumed that the wrapper code 
   uses arg1--argn for arguments. */

void Contracts::substitute_parms(String *s, ParmList *p, int method) {
  int   argnum = 1;
  char  argname[32];

  if (method) {
    Replaceid(s,"self","arg0");
    argnum++;
  }
  while (p) {
    sprintf(argname,"arg%d",argnum);
    String *name = Getattr(p,"name");
    if (name) {
      Replaceid(s,name,argname);
    }
    argnum++;
    p = nextSibling(p);
  }
}

int Contracts::emit_contract(Node *n, int method) {
  Hash  *contracts;
  Hash  *messages;
  String *c;

  ParmList *cparms;

  if (!Getattr(n, "feature:contract"))
    return SWIG_ERROR;

  /* Get contract parameters */
  cparms = Getmeta(Getattr(n, "feature:contract"), "parms");

  /*  Split contract into preassert & postassert */    
  contracts = ContractSplit(n);
  if (!contracts) return SWIG_ERROR;

  /* This messages hash is used to hold the error messages that will be displayed on
     failed contract. */

  messages = NewHash();

  /* Take the different contract expressions and clean them up a bit */
  Iterator i;
  for (i = First(contracts); i.item; i = Next(i)) {
    String *e = make_expression(i.item, n);
    substitute_parms(e, cparms, method);
    Setattr(contracts,i.key,e);

    /* Make a string containing error messages */
    Setattr(messages,i.key, NewString(e));
  }
   
  /* If we're in a class. We need to inherit other assertions. */
  if (InClass) {
    inherit_contracts(CurrentClass, n, contracts, messages);
  }

  /* Save information */
  Setattr(n,"contract:rules", contracts);
  Setattr(n,"contract:messages", messages);

  /* Okay.  Generate the contract runtime code. */
  
  if ((c = Getattr(contracts,"require:"))) {
    Setattr(n,"contract:preassert",
          NewStringf("SWIG_contract_assert(%s, \"Contract violation: require: %s\");\n",
                   c, Getattr(messages,"require:")));
  }
  if ((c = Getattr(contracts,"ensure:"))) {
    Setattr(n,"contract:postassert",
          NewStringf("SWIG_contract_assert(%s, \"Contract violation: ensure: %s\");\n",
                   c, Getattr(messages,"ensure:")));
  }
  return SWIG_OK;
}

int Contracts::cDeclaration(Node *n) {
  int ret = SWIG_OK;
  String *decl = Getattr(n,"decl");

  /* Not a function.  Don't even bother with it (for now) */
  if (!SwigType_isfunction(decl)) return SWIG_OK;

  if (Getattr(n, "feature:contract"))
    ret = emit_contract(n, (InClass && !checkAttribute(n,"storage","static")));
  return ret;
}

int Contracts::constructorDeclaration(Node  *n){
  int ret = SWIG_OK;
  InConstructor = 1;
  if (Getattr(n, "feature:contract"))
    ret = emit_contract(n,0);
  InConstructor = 0;
  return ret;
}

int Contracts::externDeclaration(Node *n) { return emit_children(n); }
int Contracts::extendDirective(Node *n)   { return emit_children(n); }
int Contracts::importDirective(Node *n)   { return emit_children(n); }
int Contracts::includeDirective(Node *n)  { return emit_children(n); }

int Contracts::classDeclaration(Node *n) {
  int ret = SWIG_OK;
  InClass = 1;
  CurrentClass = n; 
  emit_children(n);
  InClass = 0;
  CurrentClass = 0;
  return ret;
}

int Contracts::top(Node *n) {
  emit_children(n);
  return SWIG_OK;
}

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