Changes between Version 4 and Version 5 of Doc/panc/dml/functions

Timestamp:

Mar 3, 2007, 4:27:40 PM (17 years ago)

Author:

/O=GRID-FR/C=FR/O=CNRS/OU=LAL/CN=Charles Loomis

Comment:

--

Doc/panc/dml/functions

@@ -31 +31 @@
 "options" = list("noauto", "owner", "ro"); 
 # our first mount entry is the CD coming from hdc 
+"/system/mounts/0" = create("mount_cdrom", "device", "hdc"); 
+# this is exactly equivalent to the following two lines 
+"/system/mounts/0" = create("mount_cdrom"); 
+"/system/mounts/0/device" = "hdc"; 
 }}}
 
@@ -42 +46 @@
 debug("x is positive: " + to_string(x)); 
 }}}
+
+=== delete( arg:variable ) ===
+
+This function deletes the element identified by the ”variable expression” (i.e. variable name with optional 
+subscript such as foo or foo[123] or foo[123][”abc”]. . . ). 
+{{{
+# the following will put the list ("a", "c") at path "/x" 
+"/x" = { 
+x = list("a", "b", "c"); 
+delete(x[1]); 
+return(x); 
+}; 
+}}}
+
+=== error( message:string ) ===
+
+This function prints the given message on stderr and aborts the compilation. 
+
+{{{
+# user function requiring one long argument 
+define function foo = { 
+if (argc != 1) 
+error("foo(): wrong number of arguments: " + to_string(argc)); 
+if (!is_long(argv[0])) 
+error("foo(): argument is not a long"); 
+# normal processing... 
+}; 
+}}}
+
+=== escape( arg:string ) : string ===
+
+This function escape non alphanumeric characters in the given string so that it can be used inside paths, 
+for instance as an named list key. 
+
+{{{
+"/test" = escape("1+1"); 
+# will be the string "1_2b1" 
+}}}
+
+=== exists( arg:variable ) : boolean ===
+
+This function checks if the ”variable expression” (see delete function) corresponds to an existing 
+element.
+
+=== exists( path:string ) : boolean ===
+
+This function checks if the path corresponds to an existing element. 
+
+=== exists( template:string ) : boolean ===
+
+This function checks if the given template exists. 
+
+=== first( arg:resource, key:identifier, value:identifier ) : boolean ===
+
+This function resets the iterator associated with arg so that it points to its first child element; if there is 
+one (i.e. if the resource is not empty), sets the variable key to the ”key” of this element (i.e. a long if arg 
+is a list or a string if it is a nlist) and the variable value to the child element itself and return true; if key 
+or value is undef, don’t assign it; if there is no such child element, simply return false. 
+
+{{{
+# compute the sum of the elements inside numlist 
+numlist = list(1, 2, 4, 8); 
+sum = 0; 
+ok = first(numlist, k, v); 
+while (ok) { 
+sum = sum + v; 
+ok = next(numlist, k, v); 
+}; 
+# sum will be 15 
+# put the list of all the keys of table inside keys 
+table = nlist("a", 1, "b", 2, "c", 3); 
+keys = list(); 
+ok = first(table, k, v); 
+while (ok) { 
+keys[length(keys)] = k;ok = next(table, k, v);
+}; 
+# keys will be ("a", "b", "c") 
+}}}
+
+=== index ( sub:string, arg:string, [ start:long ] ) : long ===
+
+This function searches for the given substring inside the given string and returns its position from the 
+beginning of the string or -1 if not found; if the third argument is given, starts only from that position. 
+
+{{{
+"/s1" = index("foo", "abcfoodefoobar"); # 3 
+"/s2" = index("f0o", "abcfoodefoobar"); # -1 
+"/s3" = index("foo", "abcfoodefoobar", 4); # 8 
+}}}
+
+=== index ( sub:property, arg:list, [ start:long ] ) : long ===
+
+This function searches for the given property inside the given list of properties and returns its position or 
+-1 if not found; if the third argument is given, starts only from that position; it is an error if sub and arg’s 
+children are not of the same type. 
+
+{{{
+# search in a list of strings 
+"/l1" = index("foo", list("Foo", "FOO", "foo", "bar")); 
+# will be 2 
+# search in a list of longs 
+"/l2" = index(1, list(3, 1, 4, 1, 6), 2); 
+# will be 3 
+}}}
+
+=== index ( sub:property, arg:nlist, [ start:long ] ) : string ===
+
+This function searches for the given property inside the given named list of properties and returns its 
+name or the empty string if not found; if the third argument is given, skips that many matching children; 
+it is an error if sub and arg’s children are not of the same type. 
+
+{{{
+# simple color table 
+"/table" = nlist("red", 0xf00, "green", 0x0f0, "blue", 0x00f); 
+"/name1" = index(0x0f0, value("/table")); 
+# will be the string "green" 
+"/name2" = index(0x0f0, value("/table"), 1); 
+# will be the string ""
+}}}
+
+=== index ( sub:nlist, arg:list, [ start:long ] ) : long ===
+
+This function searches for the given named list inside the given list of named lists and returns its position 
+or -1 if not found; the comparison is done by comparing all the children of sub, these children must all 
+be properties; if the third argument is given, starts only from that position; it is an error if sub and arg’s 
+children are not of the same type or if their common children don’t have the same type. 
+
+{{{
+# search a record in a list of records 
+"/l1" = index(nlist("key", "foo"), list(nlist("key", "bar", "val", 101), 
+nlist("key", "foo", "val", 102))); 
+# will be 1 (i.e. the second nlist) 
+}}}
+
+=== index ( sub:nlist, arg:nlist, [ start:long ] ) : string ===
+
+This function searches for the given named list inside the given named list of named lists and returns its 
+name or the empty string if not found; if the third argument is given, skips that many matching children; 
+it is an error if sub and arg’s children are not of the same type or if their common children don’t have the 
+same type. 
+
+=== is_boolean( arg:element ) : boolean ===
+
+This function checks if the given argument is a boolean. 
+
+=== is_defined( arg:element ) : boolean ===
+
+This function checks if the given argument is defined (i.e. is anything but undef or null). 
+
+=== is_double( arg:element ) : boolean ===
+
+This function checks if the given argument is a double. 
+
+=== is_list( arg:element ) : boolean ===
+
+This function checks if the given argument is a list. 
+
+=== is_long( arg:element ) : boolean ===
+
+This function checks if the given argument is a long. 
+
+=== is_nlist( arg:element ) : boolean ===
+
+This function checks if the given argument is a nlist. 
+
+=== is_null( arg:element ) : boolean ===
+
+This function checks if the given argument has a null value (i.e. is anything but null). 
+
+=== is_property( arg:element ) : boolean ===
+
+This function checks if the given argument is a property. 
+
+=== is_resource( arg:element ) : boolean ===
+
+This function checks if the given argument is a resource. 
+
+=== is_string( arg:element ) : boolean ===
+
+This function checks if the given argument is a string. 
+
+=== key( arg:nlist, index:long ) : string ===
+
+This function returns the name of the child identified by its index, this can be used to iterate through all 
+the children of a named list. 
+
+{{{
+"/table" = nlist("red", 0xf00, "green", 0x0f0, "blue", 0x00f); 
+"/keys" = { 
+tbl = value("/table"); 
+res = ""; 
+len = length(tbl); 
+idx = 0; 
+while (idx < len) { 
+res = res + key(tbl, idx) + " "; 
+idx = idx + 1; 
+}; 
+if (length(res) > 0) 
+splice(res, -1, 1); 
+return(res); 
+}; 
+# /keys will be the string "red green blue" 
+}}}
+
+=== length( arg:string ) : long ===
+
+This function returns the length of the given string. 
+
+=== length( arg:resource ) : long ===
+
+This function returns the number of children of the given resource. 
+
+=== list( ... ) : list ===
+
+This function returns a list made of its arguments. 
+
+{{{
+# the list of mount entries is empty 
+"/system/mounts = list(); 
+# we define two DNS servers 
+"/system/dns/servers" = list("137.138.16.5", "137.138.17.5"); 
+# this machine has only one CPU 
+"/hardware/cpus" = list(create("cpu_intel_p3_850")); 
+}}}
+
+=== match( arg:string, regexp:string ) : boolean ===
+
+This function checks if the given string matches the regular expression. 
+
+{{{
+# device_t is a string that can only be "disk", "cd" or "net" 
+type device_t = string with match(self, ’ˆ(disk|cd|net)$’); 
+}}}
+
+=== matches( arg:string, regexp:string ) : list ===
+This function matches the given string against the regular expression and returns the list of captured 
+substrings, the first one being the complete matched string (i.e. $& in Perl). 
+
+{{{
+# IPv4 address in dotted number notation 
+type ipv4 = string with { 
+result = matches(self, ’ˆ(\d+)\.(\d+)\.(\d+)\.(\d+)$’); 
+if (length(result) == 0) 
+return("bad string"); 
+i = 1; 
+while (i <= 4) { 
+x = to_long(result[i]); 
+if (x > 255) 
+return("chunk " + to_string(i) + " too big: " + result[i]); 
+i = i + 1; 
+}; 
+return(true); 
+}; 
+}}}
+
+=== merge( ... ) : resource ===
+
+This function returns the resource which is the merge of its arguments which must be of the same type: 
+either all lists or all named lists; if several named lists have children of the same name, an error occurs. 
+
+{{{
+"/x" = list("a", "b", "c"); 
+"/y" = list("d", "e"); 
+"/z" = merge (value("/x"), value("/y")); 
+# /z will contain the list "a", "b", "c", "d", "e" 
+}}}
+
+=== next( arg:resource, key:identifier, value:identifier ) : boolean ===
+
+This function increments the iterator associated with arg so that it points to the next child element and 
+then behaves like first. 
+
+=== nlist( ... ) : nlist ===
+
+This function returns a named list made of its arguments which must be pairs of key (i.e. child’s name, a 
+string) and value (i.e. child’s value, an element). 
+
+{{{
+# hda1 is our root filesystem 
+"/system/mounts/0" = nlist("type", "ext2", "path", "/", "device", "hda1"); 
+# hda2 is our /var filesystem 
+"/system/mounts/1" = nlist( 
+"type", "ext2", 
+"path", "/var", 
+"device", "hda2", 
+); 
+}}}
+
+=== return( arg:element ) : element ===
+
+This function interrupts the processing of the current DML block and returns from it with the given value, 
+this is often used in user defined functions. 
+
+{{{
+function facto = { 
+  if (argv[0] < 2) return(1); 
+  return(argv[0] * facto(argv[0] - 1)); 
+}; 
+}}}
+
+=== splice ( arg:string, start:long, length:long, [ new:string ] ) : string ===
+
+This function deletes the substring identified by start and length (see substr’s documentation for de- 
+tails) and, if a fourth argument is given, replaces it with new. 
+
+{{{
+"/s1" = splice("abcde", 2, 0, "12"); # ab12cde 
+"/s2" = splice("abcde", -2, 1); # abce 
+"/s3" = splice("abcde", 2, 2, "XXX"); # abXXXe 
+}}}
+
+=== splice ( arg:list, start:long, length:long, [ new:list] ) : list ===
+
+This function deletes the children of the given list identified by start and length (see substr’s docu- 
+mentation for details) and, if a fourth argument is given, replaces them with the contents of new. 
+
+{{{
+"/l1" = splice(list("a","b","c","d","e"), 2, 0, list(1,2)); 
+# will be the list "a", "b", 1, 2, "c", "d", "e" 
+"/l2" = splice(list("a","b","c","d","e"), -2, 1); 
+# will be the list "a", "b", "c", "e" 
+"/l3" = splice(list("a","b","c","d","e"), 2, 2, list("XXX")); 
+# will be the list "a", "b", "XXX", "e" 
+}}}
+
+=== substr ( arg:string, start:long, [ length:long ] ) : string ===
+
+This function returns the part of the given string characterised by its start position (starting from 0) and 
+its length (if omitted, returns everything to the end of the string); if start is negative, starts that far from 
+the end of the string; if length is negative, leaves that many characters off the end of the string.
+
+{{{
+"/s1" = substr("abcdef", 2); # cdef 
+"/s2" = substr("abcdef", 1, 1); # b 
+"/s3" = substr("abcdef", 1, -1); # bcde 
+"/s4" = substr("abcdef", -4); # cdef 
+"/s5" = substr("abcdef", -4, 1); # c 
+"/s6" = substr("abcdef", -4, -1); # cde 
+}}}
+
+=== to_boolean( arg:property ) : boolean ===
+
+This function converts the given property into a boolean; 0 and the empty strings are considered as false, 
+everything else as true. 
+
+=== to_double( arg:property ) : double ===
+
+This function converts the given property into a double; it is an error if the given string does not represent 
+a double. 
+
+=== to_long( arg:property ) : long ===
+
+This function converts the given property into a long; it is an error if the given string does not represent 
+a long; if the argument is a double, it will be rounded to the nearest long. 
+
+=== to_string( arg:property ) : string ===
+
+This function converts the given property into a string. 
+
+=== unescape( arg:string ) : string ===
+
+This function replace escaped characters in the given string to get back the original string, this is the 
+inverse of the escape function. 
+
+=== value( path:string ) : element ===
+
+This function returns the element identified by its path (which can be an external path), an error occurs if 
+there is no such element. 
+
+{{{
+"/x" = 100; 
+"/y" = 2 * value("/x"); 
+# /y will be 200 
+# we add one DNS server to the current list 
+# (we need to use list() because merge() requires lists) 
+"/system/dns/servers" = merge(value("/system/dns/servers"), 
+list("137.138.16.5")); 
+# the RAM of this machine is the same as the machine foo 
+"/hardware/memory/size" = value("//foo/hardware/memory/size"); 
+}}}