// Dec will decrement a variable.
// args[0] - variable name
// args[1] - quantum of value to decrement
// if variable name is present in local scope it will be used,
// otherwise variable name from global scope is used.
func Dec(scope common.Scope, args ...interface{}) interface{} {
name, by := args[0].(string), int64(1)
if len(args) > 1 {
by = args[1].(int64)
}
vali, g, ok := scope.Get(name)
if ok {
scope.Set(name, vali.(int64)-by, g)
}
return ""
}
// Rangef will randomly pick a value from args[0] to args[1]
// and return the same.
// args... are expected to be in float64
func Rangef(scope common.Scope, args ...interface{}) interface{} {
rnd := scope.GetRandom()
if len(args) == 2 {
min, max := args[0].(float64), args[1].(float64)
f := (rnd.Float64() * (max - min)) + min
return f
} else if len(args) == 1 {
max := args[0].(float64)
return rnd.Float64() * max
}
panic(fmt.Errorf("atleast one argument expected for range-form\n"))
}
// Ranget will randomly pick a value from args[0] to args[1]
// and return the same.
// args... are expected to be in time.RFC3339 format
func Ranget(scope common.Scope, args ...interface{}) interface{} {
rnd := scope.GetRandom()
start, err := time.Parse(time.RFC3339, args[0].(string))
if err != nil {
panic(fmt.Errorf("parsing first argument %v: %v\n", args[0], err))
}
end, err := time.Parse(time.RFC3339, args[1].(string))
if err != nil {
panic(fmt.Errorf("parsing second argument %v: %v\n", args[0], err))
}
t := start.Add(time.Duration(rnd.Int63n(int64(end.Sub(start)))))
return t.Format(time.RFC3339)
}
// Range will randomly pick a value from args[0] to args[1]
// and return the same.
// args... are expected to be in int64
func Range(scope common.Scope, args ...interface{}) interface{} {
var min, max int64
var err error
rnd := scope.GetRandom()
if len(args) == 2 {
min, max = args[0].(int64), args[1].(int64)
if err != nil {
panic(fmt.Errorf("parsing argument %v\n", args[1]))
}
} else if len(args) == 1 {
max = args[0].(int64)
} else {
panic(fmt.Errorf("atleast one argument expected for range-form\n"))
}
return rnd.Int63n(max-min) + min
}
// Bag will fetch a random line from file and return it.
// args[0] - filename.
func Bag(scope common.Scope, args ...interface{}) interface{} {
var err error
filename := args[0].(string)
if !filepath.IsAbs(filename) {
if bagdir, _, ok := scope.GetString("_bagdir"); ok {
filename = filepath.Join(bagdir, filename)
} else if prodfile, _, ok := scope.GetString("_prodfile"); ok {
dirpath := filepath.Dir(prodfile)
filename = filepath.Join(dirpath, filename)
}
}
if filename, err = filepath.Abs(filename); err != nil {
panic(fmt.Errorf("bad filepath: %v\n", filename))
}
bagrw.RLock()
records, ok := cacheBagRecords[filename]
bagrw.RUnlock()
if !ok {
records = readBag(filename)
bagrw.Lock()
cacheBagRecords[filename] = records
bagrw.Unlock()
}
if len(records) > 0 {
rnd := scope.GetRandom()
record := records[rnd.Intn(len(records))]
if len(record) > 0 {
return record[0]
}
}
return ""
}
// BuildContext to initialize a new scope for evaluating
// production grammars. The scope contains the following
// elements,
//
// _globalForms: list of top-level S-expression definitions
// _nonterminals: list of top-level non-terminals in production
// _weights: running weights for each non-terminal rule
// _globals: global scope
// _bagdir: absolute path to directory containing bags of data
// _prodfile: absolute path to production file
// _random: reference to seeded *math.rand.Rand object
func BuildContext(
scope common.Scope,
seed uint64,
bagdir, prodfile string) common.Scope {
scope["_prodfile"] = prodfile
scope.SetBagdir(bagdir)
if seed != 0 {
scope.SetRandom(rand.New(rand.NewSource(int64(seed))))
} else {
now := time.Now().UnixNano()
scope.SetRandom(rand.New(rand.NewSource(int64(now))))
}
// verify conflicts between user provided form-names
// and builtin form-names.
for name := range scope["_nonterminals"].(common.NTForms) {
if _, ok := builtins[name]; ok {
log.Printf("warn: `%v` non-terminal is defined as builtin\n", name)
}
}
return scope.RebuildContext()
}
// Choice will randomly pick one of the passed argument
// and return back.
func Choice(scope common.Scope, args ...interface{}) interface{} {
rnd := scope.GetRandom()
return args[rnd.Intn(len(args))]
}
// Let will define a set of one or more variables in
// local scope.
// args[0], args[2] ... args[N-1] - variable name
// args[1], args[3] ... args[N] - variable value
func Let(scope common.Scope, args ...interface{}) interface{} {
for i := 0; i < len(args); i += 2 {
scope.Set(args[i].(string), args[i+1], false /*global*/)
}
return ""
}