--* From postmaster%watson.vnet.ibm.com@yktvmv.watson.ibm.com Tue Jul 5 09:20:28 1994 --* Received: from yktvmv-ob.watson.ibm.com by asharp.watson.ibm.com (AIX 3.2/UCB 5.64/930311) --* id AA25812; Tue, 5 Jul 1994 09:20:28 -0400 --* Received: from watson.vnet.ibm.com by yktvmv.watson.ibm.com (IBM VM SMTP V2R3) --* with BSMTP id 2883; Tue, 05 Jul 94 09:20:30 EDT --* Received: from YKTVMV by watson.vnet.ibm.com with "VAGENT.V1.0" --* id --* for asbugs@watson; Tue, 05 Jul 94 09:20:30 -0400 --* Received: from YKTVMV by watson.vnet.ibm.com with "VAGENT.V1.0" --* id 6947; Tue, 5 Jul 1994 09:20:29 EDT --* Received: from leonardo.watson.ibm.com by yktvmv.watson.ibm.com --* (IBM VM SMTP V2R3) with TCP; Tue, 05 Jul 94 09:20:28 EDT --* Received: by leonardo.watson.ibm.com (AIX 3.2/UCB 5.64/920123) --* id AA12891; Tue, 5 Jul 1994 09:15:44 -0400 --* Date: Tue, 5 Jul 1994 09:15:44 -0400 --* From: jenks@leonardo.watson.ibm.com --* X-External-Networks: yes --* Message-Id: <9407051315.AA12891@leonardo.watson.ibm.com> --* To: asbugs@watson.ibm.com --* Subject: [3] segmentation violation [/u/jenks/dimacs94/ex.pm/xtree.as][?] --@ Fixed by: SSD Tue Mar 21 12:32:52 EST 1995 --@ Tested by: none --@ Summary: Segmentation fault no longer appears. Now gives valid user error messages. --+ --> testint --+ --> testrun --+ #include "aslib.as" --+ --+ Xtree(S: BasicType): BasicType with { --+ empty: %; --+ tree: S -> %; --+ tree: (S, List %) -> %; --+ bracket: Tuple Union(S,%) -> %; --+ leaf?: % -> Boolean; --+ empty?: % -> Boolean; --+ generator: % -> Generator S; --+ node: % -> S; --+ child: (%, Integer) -> %; --+ preorder: % -> Generator S --+ } == add { --+ Rep ==> Record(node: S, args: List %); --+ import from Rep; --+ import from List %; --+ tree(s: S): % == per [s, nil]; --+ tree(s: S, l: List %): % == per [s, l]; --+ empty: % == nil$Pointer pretend %; --+ sample: % == empty; --+ empty?(t: %): Boolean == nil?(t pretend Pointer)$Pointer; --+ leaf? (t: %): Boolean == empty? ((rep t).args); --+ node(t: %): S == (rep t) . node; --+ --+ child(t: %, n: Integer): % == { --+ empty? t => error "Taking a part of a non-empty tree"; --+ n <= 0 => error "child must take a positive index"; --+ apply((rep t) . args, n pretend SingleInteger) --+ } --+ --+ bracket(tup: Tuple Union(S, %)): % == { --+ u: List Tuple Union(S, %) := [tup]; --+ root := { --+ first u case S => first u; --+ error "first element must be a scalar" --+ } --+ branches := { --+ acc: List % := nil; --+ for x in rest u repeat { --+ y: % := { --+ x case S => tree x; --+ x --+ } --+ acc := cons(x,acc); --+ } --+ reverse acc --+ } --+ tree(root, branches) --+ } --+ --+ generator(l: %): Generator S == generate { --+ yield l . node; --+ for x in l . args repeat yield x --+ } --+ --+ (t1: %) = (t2: %): Boolean == { --+ import from S; --+ empty? t1 and empty? t2 => true; --+ empty? t1 or empty? t2 => false; --+ (rep t1).node = (rep t2).node and (rep t1).args = (rep t2).args --+ } --+ --+ preorder(t: %) : Generator S == generate { not empty? t => { --+ yield node t; --+ for branch in (rep t).args repeat --+ for val in preorder branch repeat yield val --+ }} --+ --+ (outp: TextWriter) << (t: %): TextWriter == { --+ import from String; --+ import from S; --+ empty? t => outp << "empty"; --+ leaf? t => outp << (rep t) . node; --+ outp << "[" << (rep t) . node; --+ for x in (rep t) . args repeat outp << ", " << x; --+ outp << "]" --+ } --+ } --+ --+ -- Testing your solution --+ f(): () == { --+ import from String; --+ import from TextWriter; --+ import from Xtree(String); --+ import from List(Xtree(String)); --+ t := tree "a"; --+ print << "The tree is " << t; --+ -- t := tree("*", [tree("+", [tree "a",tree "b"]), --+ -- tree("-", [tree "c",tree "d"])]); --+ print << "The tree is " << t; --+ print << "Preorder: "; --+ for s in preorder t repeat print << s << " "; --+ print << newline; --+ --+ } --+ --+ f(); --+ --> testint --> testrun #include "aslib.as" Xtree(S: BasicType): BasicType with { empty: %; tree: S -> %; tree: (S, List %) -> %; bracket: Tuple Union(S,%) -> %; leaf?: % -> Boolean; empty?: % -> Boolean; generator: % -> Generator S; node: % -> S; child: (%, Integer) -> %; preorder: % -> Generator S } == add { Rep ==> Record(node: S, args: List %); import from Rep; import from List %; tree(s: S): % == per [s, nil]; tree(s: S, l: List %): % == per [s, l]; empty: % == nil$Pointer pretend %; sample: % == empty; empty?(t: %): Boolean == nil?(t pretend Pointer)$Pointer; leaf? (t: %): Boolean == empty? ((rep t).args); node(t: %): S == (rep t) . node; child(t: %, n: Integer): % == { empty? t => error "Taking a part of a non-empty tree"; n <= 0 => error "child must take a positive index"; apply((rep t) . args, n pretend SingleInteger) } bracket(tup: Tuple Union(S, %)): % == { u: List Tuple Union(S, %) := [tup]; root := { first u case S => first u; error "first element must be a scalar" } branches := { acc: List % := nil; for x in rest u repeat { y: % := { x case S => tree x; x } acc := cons(x,acc); } reverse acc } tree(root, branches) } generator(l: %): Generator S == generate { yield l . node; for x in l . args repeat yield x } (t1: %) = (t2: %): Boolean == { import from S; empty? t1 and empty? t2 => true; empty? t1 or empty? t2 => false; (rep t1).node = (rep t2).node and (rep t1).args = (rep t2).args } preorder(t: %) : Generator S == generate { not empty? t => { yield node t; for branch in (rep t).args repeat for val in preorder branch repeat yield val }} (outp: TextWriter) << (t: %): TextWriter == { import from String; import from S; empty? t => outp << "empty"; leaf? t => outp << (rep t) . node; outp << "[" << (rep t) . node; for x in (rep t) . args repeat outp << ", " << x; outp << "]" } } -- Testing your solution f(): () == { import from String; import from TextWriter; import from Xtree(String); import from List(Xtree(String)); t := tree "a"; print << "The tree is " << t; -- t := tree("*", [tree("+", [tree "a",tree "b"]), -- tree("-", [tree "c",tree "d"])]); print << "The tree is " << t; print << "Preorder: "; for s in preorder t repeat print << s << " "; print << newline; } f();