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expression.go
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expression.go
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package gorpn
import (
"fmt"
"math"
"reflect"
"sort"
"strconv"
"strings"
"time"
)
// DefaultDelimiter specifies the delimiter character used between tokens in an RPN expression. For
// instance, in the expression `12,age,*`, the delimiter is the comma. The evaluator can use a
// different delimiter character by invoking the Delimiter() function.
const DefaultDelimiter = ','
// DefaultSecondsPerInterval specifies the number of seconds between successive data values in a
// time-series. It can be overridden by SecondsPerInterval() function.
const DefaultSecondsPerInterval = 300
// type arityTuple [3]int
type arityTuple struct {
popCount, floatOffset, floatCount, nonOperatorOffset, nonOperatorCount int
}
// arity resolves to the number of items an operation must pop, and
// how many of those must be floats
var arity = map[string]arityTuple{
"%": {2, 2, 0, 0, 0},
"*": {2, 2, 0, 0, 0},
"+": {2, 2, 0, 0, 0},
"-": {2, 2, 0, 0, 0},
"/": {2, 2, 0, 0, 0},
"ABS": {1, 1, 1, 0, 0},
"ADDNAN": {2, 2, 2, 0, 0},
"ATAN": {1, 1, 1, 0, 0},
"ATAN2": {2, 2, 2, 0, 0},
"AVG": {1, 1, 1, 0, 0}, // other operands must be floats
"CEIL": {1, 1, 1, 0, 0},
"COPY": {1, 1, 1, 0, 0}, // other operands cannot be operators
"COS": {1, 1, 1, 0, 0},
"DEG2RAD": {1, 1, 1, 0, 0},
"DEPTH": {0, 0, 0, 0, 0},
"DUP": {1, 0, 0, 1, 1}, // equivalent to: 1,COPY
"EQ": {2, 0, 0, 2, 2},
"EXC": {2, 0, 0, 2, 2}, // equivalent to: 2,REV
"EXP": {1, 1, 1, 0, 0},
"FLOOR": {1, 1, 1, 0, 0},
"GE": {2, 0, 0, 2, 2},
"GT": {2, 0, 0, 2, 2},
"IF": {3, 3, 1, 2, 2}, // a,b,c,IF
"INDEX": {1, 1, 1, 0, 0}, // other operands cannot be operators
"ISINF": {1, 1, 1, 0, 0},
"LE": {2, 0, 0, 2, 2},
"LIMIT": {3, 3, 3, 0, 0},
"LOG": {1, 1, 1, 0, 0},
"LT": {2, 0, 0, 2, 2},
"MAD": {1, 1, 1, 0, 0}, // other operands must be floats
"MAX": {2, 0, 0, 2, 2},
"MAXNAN": {2, 0, 0, 2, 2},
"MEDIAN": {1, 1, 1, 0, 0}, // other operands must be floats
"MIN": {2, 0, 0, 2, 2},
"MINNAN": {2, 0, 0, 2, 2},
"NE": {2, 0, 0, 2, 2},
"PERCENT": {2, 2, 2, 0, 0}, // n,m,PERCENT (a,b,c,95,3,PERCENT -> find 95percentile of a,b,c)
"POP": {1, 0, 0, 0, 0},
"POW": {2, 2, 0, 0, 0},
"RAD2DEG": {1, 1, 1, 0, 0},
"REV": {1, 1, 1, 0, 0}, // other operands cannot be operators
"ROLL": {2, 2, 2, 0, 0}, // n,m,ROLL (rotate the top n elements of the stack by m)
"SIN": {1, 1, 1, 0, 0},
"SMAX": {1, 1, 1, 0, 0}, // other operands must be floats
"SMIN": {1, 1, 1, 0, 0}, // other operands must be floats
"SORT": {1, 1, 1, 0, 0}, // other operands must be floats
"SQRT": {1, 1, 1, 0, 0},
"STDEV": {1, 1, 1, 0, 0}, // other operands must be floats
"TREND": {2, 1, 1, 2, 1}, // label,count,TREND
"TRENDNAN": {2, 1, 1, 2, 1}, // label,count,TRENDNAN
"UN": {1, 1, 1, 0, 0},
}
// ExpectedFloat error is returned if a different data type is
// discovered where a float64 value is required.
type ExpectedFloat struct {
v interface{}
}
// Error returns the error string representation for ExpectedFloat errors.
func (e ExpectedFloat) Error() string {
return fmt.Sprintf("expected float: %T", e.v)
}
// ErrBadBindingType error is returned when one or more bindings have
// a type that is neither a float64 nor a slice of float64 values.
type ErrBadBindingType struct {
t string
}
// Error returns the error string representation for ErrBadBindingType
// errors.
func (e ErrBadBindingType) Error() string {
return "bad binding type for " + string(e.t)
}
// ErrOpenBindings error is returned when one or more open bindings
// remain when evaluating a RPN Expression.
type ErrOpenBindings []string
// Error returns the error string representation for ErrOpenVariables
// errors.
func (e ErrOpenBindings) Error() string {
return "open bindings: " + strings.Join(e, ",")
}
// ErrSyntax error is returned if the specified RPN expression
// does not evaluate because of a syntax error.
type ErrSyntax struct {
Message string
Err error
}
// Error returns the error string representation for ErrSyntax errors.
func (e ErrSyntax) Error() string {
if e.Err == nil {
return "syntax error " + e.Message
}
return "syntax error " + e.Message + ": " + e.Err.Error()
}
func newErrSyntax(a ...interface{}) ErrSyntax {
var err error
var format, message string
var ok bool
if len(a) == 0 {
return ErrSyntax{"no reason given", nil}
}
// if last item is error: save it
if err, ok = a[len(a)-1].(error); ok {
a = a[:len(a)-1] // pop it
}
// if items left, first ought to be format string
if len(a) > 0 {
if format, ok = a[0].(string); ok {
a = a[1:] // unshift
message = fmt.Sprintf(format, a...)
}
}
if message != "" {
message = ": " + message
}
return ErrSyntax{message, err}
}
// ExpressionConfigurator represents a function that modifies an RPN Expression.
type ExpressionConfigurator func(*Expression) error
// Delimiter allows changing the expected delimiter for an RPN Expression from the default
// delimiter, the comma. Changing the delimiter to one of the math operators is not supported.
//
// func example() {
// exp, err := gorpn.New("42|13|2|MEDIAN", gorpn.Delimiter('|'))
// if err != nil {
// panic(err)
// }
// value, err := exp.Evaluate(nil)
// if err != nil {
// panic(err)
// }
// fmt.Println("value:", value)
// }
func Delimiter(someDelimiter rune) ExpressionConfigurator {
return func(e *Expression) error {
if _, ok := arity[string(someDelimiter)]; ok {
return newErrSyntax("cannot use %c operator for delimiter", someDelimiter)
}
e.delimiter = someDelimiter
return nil
}
}
// SecondsPerInterval allows changing the expected number of seconds per interval to be used when
// evaluating an RPN Expression from the default value of 300..
//
// func example() {
// exp, err := gorpn.New("42,13,2,MEDIAN", gorpn.SecondsPerInterval(60))
// if err != nil {
// panic(err)
// }
// }
func SecondsPerInterval(seconds float64) ExpressionConfigurator {
return func(e *Expression) error {
if seconds <= 0 {
return newErrSyntax("cannot use %d seconds as interval", seconds)
}
e.secondsPerInterval = seconds
return nil
}
}
// Expression represents a RPN expression.
type Expression struct {
delimiter rune
openBindings map[string]int // count of number of instances
secondsPerInterval float64
tokens []interface{} // components of the expression
performTimeSubstitutions bool
// work area
scratchSize int // how much work area this needs
scratchHead int // index of top of scratch and isFloat slices
scratch []interface{} // work area where calculations are done
isFloat []bool // true iff corresponding scratch item is a float64 (consider using reflection, but might be slower)
}
// New returns a new RPN Expression based on some expression. Creating a new RPN expression
// automatically invokes the Partial method on the expression to ensure the most reduced form of the
// RPN expression is returned. See notes on the Partial method for additional reasoning behind this
// decision.
//
// expression, err := gorpn.New("60,24,*")
// if err != nil {
// panic(err)
// }
// result, err := expression.Evaluate(nil)
// if err != nil {
// panic(err)
// }
func New(someExpression string, setters ...ExpressionConfigurator) (*Expression, error) {
if someExpression == "" {
return nil, ErrSyntax{"empty expression", nil}
}
e := &Expression{
delimiter: DefaultDelimiter,
secondsPerInterval: DefaultSecondsPerInterval,
}
for _, setter := range setters {
if err := setter(e); err != nil {
return nil, err
}
}
tokens := strings.Split(someExpression, string(e.delimiter))
e.scratchSize = len(tokens)
e.tokens = make([]interface{}, e.scratchSize)
for idx, token := range tokens {
switch token {
case "NOW", "TIME", "LTIME", "NEWDAY", "NEWWEEK", "NEWMONTH", "NEWYEAR":
e.performTimeSubstitutions = true
case "DUP":
e.scratchSize++
}
e.tokens[idx] = token
}
// scratchSize may be larger than it was before above loop
e.scratch = make([]interface{}, e.scratchSize)
e.isFloat = make([]bool, e.scratchSize)
return e.Partial(nil)
}
// Evaluate evaluates the Expression after applying the parameter bindings. An empty map or, more
// idiomatically a nil value, is given to Evaluate for RPN expressions that have no open bindings.
//
// expression, err := gorpn.New("60,24,*")
// if err != nil {
// panic(err)
// }
// result, err := expression.Evaluate(nil)
// if err != nil {
// panic(err)
// }
//
// For RPN expressions that have open bindings, simply create a map and set keys to the parameter
// names and their respective values to their desired bound values.
//
// expression, err := gorpn.New("12,age,*")
// if err != nil {
// panic(err)
// }
// bindings := map[string]interface{} {
// "age": 21,
// }
// result, err := expression.Evaluate(bindings)
// if err != nil {
// panic(err)
// }
func (e *Expression) Evaluate(bindings map[string]interface{}) (float64, error) {
var err error
if err = e.simplify(bindings); err != nil {
return 0, err
}
var openBindings []string
for k, v := range e.openBindings {
if v > 0 {
openBindings = append(openBindings, k)
}
}
if len(openBindings) > 0 {
return 0, ErrOpenBindings(openBindings)
}
if e.scratchHead != 1 {
return 0, newErrSyntax("extra parameters: %v", e.scratch)
}
result, ok := e.scratch[0].(float64)
if !ok {
return 0, ExpectedFloat{e.scratch[0]}
}
return result, nil
}
// OpenBindings returns a slice of strings representing the remaining open
// bindings in the Expression.
func (e *Expression) OpenBindings() []string {
l := len(e.openBindings)
if l == 0 {
return nil
}
openBindings := make([]string, 0, l)
for k, v := range e.openBindings {
if v > 0 {
openBindings = append(openBindings, k)
}
}
return openBindings
}
// String returns the string representation of an Expression.
//
// func example() {
// exp, err := gorpn.New("5,3,+,foo,*")
// if err != nil {
// panic(err)
// }
// s := exp.String() // "8,foo,*"
// }
func (e Expression) String() string {
strs := make([]string, len(e.tokens))
for idx, v := range e.tokens {
switch v.(type) {
case float64:
switch {
case math.IsNaN(v.(float64)):
// strs[idx] = "NaN" // would prefer this
strs[idx] = "UNKN" // don't like this
case math.IsInf(v.(float64), 1):
strs[idx] = "INF"
case math.IsInf(v.(float64), -1):
strs[idx] = "NEGINF"
default:
strs[idx] = fmt.Sprint(v)
}
case string:
strs[idx] = v.(string)
default:
strs[idx] = fmt.Sprint(v)
}
}
return strings.Join(strs, string(e.delimiter))
}
// Partial creates a new Expression by partial application of the parameter bindings. With the
// additional bindings, it attempts to further simplify the expression. Many RPN expressions are
// machine built, and then evaluated hundreds of thousands of times. The Partial method will
// simplify all possible operations on the expression and return a new expression
//
// func example1() {
// // Recall that New invokes Partial on your behalf.
// // (below is example actually found in config file)
// exp, err := gorpn.New("0,0,GT,qps,0,0,EQ,-2,0,IF,IF")
// if err != nil {
// panic(err)
// }
// s := exp.String() // "2"
// }
//
// func example2() {
// // Recall that New invokes Partial on your behalf.
// // (below is example actually found in config file)
// exp, err := gorpn.New("1,0,GT,qps,-2,IF")
// if err != nil {
// panic(err)
// }
// s := exp.String() // "qps"
// }
//
// While simplification of the initial RPN is great, there are many times where you might want to
// create a new expression with some of the variables bound to a particular set of values. The new
// expression will be further optimized for running many times.
//
// func example2() {
// // Recall that New invokes Partial on your behalf.
// exp1, err := gorpn.New("foo,1000,*,bar,3,+,/")
// if err != nil {
// panic(err)
// }
// s1 := exp1.String() // "foo,1000,*,bar,3,+,/"
//
// exp2, err := exp1.Partial(map[string]interface{}{"bar":13})
// if err != nil {
// panic(err)
// }
// s2 := exp2.String() // "foo,1000,*,16,/"
// }
//
func (e *Expression) Partial(bindings map[string]interface{}) (*Expression, error) {
// NOTE: We leave exp.performTimeSubstitutions as its default boolean value of false,
// preventing time substitutions from being made during this simplify operation
exp := &Expression{
delimiter: e.delimiter,
secondsPerInterval: e.secondsPerInterval,
tokens: make([]interface{}, len(e.tokens)),
scratchSize: e.scratchSize,
scratch: make([]interface{}, e.scratchSize),
isFloat: make([]bool, e.scratchSize),
}
copy(exp.tokens, e.tokens)
if err := exp.simplify(bindings); err != nil {
return nil, err
}
// exp will need to know about time when Evaluate is called on it
exp.performTimeSubstitutions = e.performTimeSubstitutions
// promote what's remaining in work area to new simplified stored program
exp.tokens = exp.tokens[:exp.scratchHead] // first, shrink tokens slice
copy(exp.tokens, exp.scratch) // then copy
return exp, nil
}
func (e Expression) valid(bindings map[string]interface{}) bool {
err := e.simplify(bindings)
if err != nil {
return false
}
if len(e.openBindings) > 0 {
for k := range e.openBindings {
bindings[k] = 0 // FIXME: some bindings will need series rather than number
}
return e.valid(bindings)
}
if e.scratchHead != 1 {
return false
}
return e.isFloat[0]
}
func epochToJuliet(secondsSinceEpoch int) (time.Time, int) {
julietTime := time.Unix(int64(secondsSinceEpoch), 0) // Juliet time zone is "local" time zone
_, julietOffset := julietTime.Zone()
return julietTime, julietOffset
}
func isFirstOfDay(jSeconds, secondsPerInterval float64) float64 {
// is julietTime first datum of day?
const secondsPerDay = 86400
js := int(jSeconds)
tLeft := (int(js) / secondsPerDay) * secondsPerDay
tRight := tLeft + int(secondsPerInterval)
if ijts := js; ijts < tLeft || ijts > tRight {
return 0
}
return 1
}
func (e *Expression) simplify(bindings map[string]interface{}) error {
// NOTE: scratch is not local variable so Partial has access to it
// TODO: change method signature to pass it back and make it local
var err error
bindings, err = coerceMapValuesToFloat64(bindings)
if err != nil {
return err
}
// with a fresh start comes fresh workspace
e.scratchHead = 0
e.openBindings = make(map[string]int)
// heisenberg principle, realized: it takes time to observe the time, so do it only once
var isTimeSet bool
var nowSeconds, jTimeSeconds, zTimeSeconds float64
var jTime time.Time
if e.performTimeSubstitutions {
nowSeconds = float64(time.Now().Unix())
// if TIME binding provided, then we can support many more RPN operators
if epoch, ok := bindings["TIME"]; ok {
zTimeSeconds, isTimeSet = epoch.(float64)
if !isTimeSet {
return newErrSyntax("TIME ought to be bound to number rather than %T", epoch)
}
var jo int
jTime, jo = epochToJuliet(int(zTimeSeconds))
jTimeSeconds = float64(jTime.Unix() + int64(jo))
}
// // ??? not sure if we want this
// // ??? also, if we have LTIME, we could get TIME, so this needs to be figured out
// if epoch, ok := bindings["LTIME"]; ok {
// jTimeSeconds, isTimeSet = epoch.(float64)
// if !isTimeSet {
// return newErrSyntax("LTIME ought to be bound to number rather than %T", epoch)
// }
// }
}
// variables outside of loop to reduce allocations
var cannotSimplify, isFloat, ok, stackUpdated, firstNaN, secondNaN bool
var total, value float64
var argIdx, additionalArgumentCount, indexOfFirstArg, itemIdx, tokIdx, used int
var opArity arityTuple
var result, tok interface{}
// tokens is our stored program, and scratch is our work area
for tokIdx, tok = range e.tokens {
switch token := tok.(type) {
case float64:
e.scratch[e.scratchHead] = token
e.isFloat[e.scratchHead] = true
e.scratchHead++
case string:
switch token {
case "DAY":
e.scratch[e.scratchHead] = 86400.0
e.isFloat[e.scratchHead] = true
e.scratchHead++
case "HOUR":
e.scratch[e.scratchHead] = 3600.0
e.isFloat[e.scratchHead] = true
e.scratchHead++
case "INF":
e.scratch[e.scratchHead] = math.Inf(1)
e.isFloat[e.scratchHead] = true
e.scratchHead++
case "LTIME":
if isTimeSet {
e.scratch[e.scratchHead] = jTimeSeconds
} else {
e.openBindings["TIME"] = e.openBindings["TIME"] + 1 // NOTE: actually requires TIME to be bound
e.scratch[e.scratchHead] = token
}
e.isFloat[e.scratchHead] = isTimeSet
e.scratchHead++
case "MINUTE":
e.scratch[e.scratchHead] = 60.0
e.isFloat[e.scratchHead] = true
e.scratchHead++
case "NEGINF":
e.scratch[e.scratchHead] = math.Inf(-1)
e.isFloat[e.scratchHead] = true
e.scratchHead++
case "NEWDAY":
if isTimeSet {
e.scratch[e.scratchHead] = isFirstOfDay(jTimeSeconds, e.secondsPerInterval)
} else {
e.openBindings["TIME"] = e.openBindings["TIME"] + 1 // NOTE: actually requires TIME to be bound
e.scratch[e.scratchHead] = token
}
e.isFloat[e.scratchHead] = isTimeSet
e.scratchHead++
case "NEWMONTH":
if isTimeSet {
if jTime.Day() == 1 {
e.scratch[e.scratchHead] = isFirstOfDay(jTimeSeconds, e.secondsPerInterval)
} else {
e.scratch[e.scratchHead] = 0.0
}
} else {
e.openBindings["TIME"] = e.openBindings["TIME"] + 1 // NOTE: actually requires TIME to be bound
e.scratch[e.scratchHead] = token
}
e.isFloat[e.scratchHead] = isTimeSet
e.scratchHead++
case "NEWWEEK":
if isTimeSet {
if jTime.Weekday() == time.Sunday {
e.scratch[e.scratchHead] = isFirstOfDay(jTimeSeconds, e.secondsPerInterval)
} else {
e.scratch[e.scratchHead] = 0.0
}
} else {
e.openBindings["TIME"] = e.openBindings["TIME"] + 1 // NOTE: actually requires TIME to be bound
e.scratch[e.scratchHead] = token
}
e.isFloat[e.scratchHead] = isTimeSet
e.scratchHead++
case "NEWYEAR":
if isTimeSet {
if _, m, d := jTime.Date(); m == 1 && d == 1 {
e.scratch[e.scratchHead] = isFirstOfDay(jTimeSeconds, e.secondsPerInterval)
} else {
e.scratch[e.scratchHead] = 0.0
}
} else {
e.openBindings["TIME"] = e.openBindings["TIME"] + 1 // NOTE: actually requires TIME to be bound
e.scratch[e.scratchHead] = token
}
e.isFloat[e.scratchHead] = isTimeSet
e.scratchHead++
case "NOW":
if e.performTimeSubstitutions {
e.scratch[e.scratchHead] = nowSeconds
} else {
e.scratch[e.scratchHead] = token
e.openBindings[token] = e.openBindings[token] + 1
}
e.isFloat[e.scratchHead] = e.performTimeSubstitutions
e.scratchHead++
case "STEPWIDTH":
e.scratch[e.scratchHead] = e.secondsPerInterval
e.isFloat[e.scratchHead] = true
e.scratchHead++
case "TIME":
if isTimeSet {
e.scratch[e.scratchHead] = zTimeSeconds
} else {
e.scratch[e.scratchHead] = token
e.openBindings["TIME"] = e.openBindings["TIME"] + 1
}
e.isFloat[e.scratchHead] = isTimeSet
e.scratchHead++
case "UNKN":
e.scratch[e.scratchHead] = math.NaN()
e.isFloat[e.scratchHead] = true
e.scratchHead++
case "WEEK":
e.scratch[e.scratchHead] = 604800.0
e.isFloat[e.scratchHead] = true
e.scratchHead++
case "":
return newErrSyntax("empty token")
default:
if opArity, ok = arity[token]; ok {
additionalArgumentCount = 0
cannotSimplify = false
stackUpdated = false
// ??? popCount = floatCount + nonOperatorCount
if e.scratchHead < opArity.popCount {
return newErrSyntax("not enough parameters: operator %s requires %d operands", token, opArity.popCount)
}
indexOfFirstArg = e.scratchHead - opArity.popCount
// fmt.Println("FLOAT CHECK: e.tokens:", e.tokens, "e.scratch:", e.scratch[:e.scratchHead], "opArity:", opArity, "floatOffset:", opArity.floatOffset, "floatCount:", opArity.floatCount)
for argIdx = e.scratchHead - opArity.floatOffset; argIdx < e.scratchHead-opArity.floatOffset+opArity.floatCount; argIdx++ {
// fmt.Printf("argIndex: %d; scratch: %v\n", argIdx, e.scratch[argIdx])
if _, isFloat = e.scratch[argIdx].(float64); !isFloat {
// fmt.Println("found non float:", e.scratch[argIdx])
cannotSimplify = true
break
}
}
// fmt.Println("NOT OPERATOR CHECK: e.tokens:", e.tokens, "e.scratch:", e.scratch[:e.scratchHead], "opArity.nonOperatorOffset:", opArity.nonOperatorOffset, "opArity.nonOperatorCount:", opArity.nonOperatorCount)
for argIdx = e.scratchHead - opArity.nonOperatorOffset; argIdx < e.scratchHead-opArity.nonOperatorOffset+opArity.nonOperatorCount; argIdx++ {
// fmt.Printf("argIndex: %d; scratch: %v\n", argIdx, e.scratch[argIdx])
if !e.isFloat[argIdx] {
result = e.scratch[argIdx]
if _, ok = arity[result.(string)]; ok {
// fmt.Println("found operator:", e.scratch[argIdx])
cannotSimplify = true
break
}
}
}
if !cannotSimplify {
switch token {
case "+":
if e.isFloat[indexOfFirstArg] { // a is float
if e.isFloat[indexOfFirstArg+1] { // b is also float
result = e.scratch[indexOfFirstArg].(float64) + e.scratch[indexOfFirstArg+1].(float64)
} else if a := e.scratch[indexOfFirstArg].(float64); a == 0 {
result = e.scratch[indexOfFirstArg+1]
} else {
cannotSimplify = true
}
} else if e.isFloat[indexOfFirstArg+1] { // only b is float
if b := e.scratch[indexOfFirstArg+1].(float64); b == 0 {
result = e.scratch[indexOfFirstArg]
} else {
cannotSimplify = true
}
} else { // neither is float
cannotSimplify = true
}
case "-":
if e.isFloat[indexOfFirstArg] { // a is float
if e.isFloat[indexOfFirstArg+1] { // b is also float
result = e.scratch[indexOfFirstArg].(float64) - e.scratch[indexOfFirstArg+1].(float64)
} else { // only a is float
cannotSimplify = true
}
} else if e.isFloat[indexOfFirstArg+1] { // only b is float
if b := e.scratch[indexOfFirstArg+1].(float64); b == 0 {
result = e.scratch[indexOfFirstArg]
} else {
cannotSimplify = true
}
} else { // neither is float
cannotSimplify = true
}
case "*":
if e.isFloat[indexOfFirstArg] { // a is float
if e.isFloat[indexOfFirstArg+1] { // b is also float
result = e.scratch[indexOfFirstArg].(float64) * e.scratch[indexOfFirstArg+1].(float64)
} else if a := e.scratch[indexOfFirstArg].(float64); a == 0 {
result = 0
} else if a == 1 {
result = e.scratch[indexOfFirstArg+1]
} else {
cannotSimplify = true
}
} else if e.isFloat[indexOfFirstArg+1] { // only b is float
if b := e.scratch[indexOfFirstArg+1].(float64); b == 0 {
result = 0
} else if b == 1 {
result = e.scratch[indexOfFirstArg]
} else {
cannotSimplify = true
}
} else { // neither is float
cannotSimplify = true
}
case "/":
if e.isFloat[indexOfFirstArg] { // a is float
if e.isFloat[indexOfFirstArg+1] { // b is also float
result = e.scratch[indexOfFirstArg].(float64) / e.scratch[indexOfFirstArg+1].(float64)
} else if a := e.scratch[indexOfFirstArg].(float64); a == 0 {
result = float64(0)
} else {
cannotSimplify = true
}
} else if e.isFloat[indexOfFirstArg+1] { // only b is float
if b := e.scratch[indexOfFirstArg+1].(float64); b == 0 {
result = math.NaN()
} else if b == 1 {
result = e.scratch[indexOfFirstArg]
} else {
cannotSimplify = true
}
} else { // neither is float
cannotSimplify = true
}
case "%":
if e.isFloat[indexOfFirstArg] { // a is float
if e.isFloat[indexOfFirstArg+1] { // b is also float
result = math.Mod(e.scratch[indexOfFirstArg].(float64), e.scratch[indexOfFirstArg+1].(float64))
} else {
cannotSimplify = true
}
} else if e.isFloat[indexOfFirstArg+1] { // only b is float
if b := e.scratch[indexOfFirstArg+1].(float64); b == 0 {
result = math.NaN()
} else if b == 1 {
result = float64(0)
} else {
cannotSimplify = true
}
} else { // neither is float
cannotSimplify = true
}
case "ABS":
result = math.Abs(e.scratch[indexOfFirstArg].(float64))
case "ADDNAN":
firstNaN = math.IsNaN(e.scratch[indexOfFirstArg].(float64))
secondNaN = math.IsNaN(e.scratch[indexOfFirstArg+1].(float64))
if !firstNaN && !secondNaN {
result = e.scratch[indexOfFirstArg].(float64) + e.scratch[indexOfFirstArg+1].(float64)
} else if !firstNaN {
result = e.scratch[indexOfFirstArg]
} else {
result = e.scratch[indexOfFirstArg+1]
}
case "ATAN":
result = math.Atan(e.scratch[indexOfFirstArg].(float64))
case "ATAN2":
result = math.Atan2(e.scratch[indexOfFirstArg+1].(float64), e.scratch[indexOfFirstArg].(float64))
case "AVG":
if math.IsNaN(e.scratch[indexOfFirstArg].(float64)) || math.IsInf(e.scratch[indexOfFirstArg].(float64), 1) || math.IsInf(e.scratch[indexOfFirstArg].(float64), -1) || e.scratch[indexOfFirstArg].(float64) <= 0 {
return newErrSyntax("%s operator requires positive finite integer: %v", token, e.scratch[indexOfFirstArg])
}
additionalArgumentCount = int(e.scratch[indexOfFirstArg].(float64))
if additionalArgumentCount > e.scratchHead-1 {
return newErrSyntax("%s operand requires %d items, but only %d on stack", token, additionalArgumentCount, e.scratchHead-1)
}
total = 0
used = 0
for argIdx = indexOfFirstArg - additionalArgumentCount; argIdx < indexOfFirstArg; argIdx++ {
if !e.isFloat[argIdx] {
cannotSimplify = true
break
}
if !math.IsNaN(e.scratch[argIdx].(float64)) {
total += e.scratch[argIdx].(float64)
used++
}
}
if !cannotSimplify {
result = total / float64(used)
}
case "CEIL":
result = math.Ceil(e.scratch[indexOfFirstArg].(float64))
case "COPY":
if math.IsNaN(e.scratch[indexOfFirstArg].(float64)) || math.IsInf(e.scratch[indexOfFirstArg].(float64), 1) || math.IsInf(e.scratch[indexOfFirstArg].(float64), -1) || e.scratch[indexOfFirstArg].(float64) <= 0 {
return newErrSyntax("%s operator requires positive finite integer: %v", token, e.scratch[indexOfFirstArg])
}
additionalArgumentCount = int(e.scratch[indexOfFirstArg].(float64))
if additionalArgumentCount > e.scratchHead-1 {
return newErrSyntax("%s operand requires %d items, but only %d on stack", token, additionalArgumentCount, e.scratchHead-1)
}
for argIdx = indexOfFirstArg - additionalArgumentCount; argIdx < indexOfFirstArg; argIdx++ {
if !e.isFloat[argIdx] {
if _, ok = arity[e.scratch[argIdx].(string)]; ok {
cannotSimplify = true
break
}
}
}
if !cannotSimplify {
e.scratchHead--
if e.scratchHead-1+additionalArgumentCount > cap(e.scratch) {
// COPY requires larger scratch and isFloat slices
scratch := make([]interface{}, e.scratchHead+additionalArgumentCount)
copy(scratch, e.scratch)
e.scratch = scratch
isFloat := make([]bool, e.scratchHead+additionalArgumentCount)
copy(isFloat, e.isFloat)
e.isFloat = isFloat
}
for argIdx = indexOfFirstArg - additionalArgumentCount; argIdx < indexOfFirstArg; argIdx++ {
e.scratch[e.scratchHead] = e.scratch[argIdx]
e.isFloat[e.scratchHead] = e.isFloat[argIdx]
e.scratchHead++
}
stackUpdated = true
}
case "COS":
result = math.Cos(e.scratch[indexOfFirstArg].(float64))
case "DEG2RAD":
result = e.scratch[indexOfFirstArg].(float64) * math.Pi / 180
case "DEPTH":
e.scratch[e.scratchHead] = e.scratchHead
e.isFloat[e.scratchHead] = true
e.scratchHead++
stackUpdated = true
case "DUP":
e.scratch[e.scratchHead] = e.scratch[e.scratchHead-1]
e.isFloat[e.scratchHead] = e.isFloat[e.scratchHead-1]
e.scratchHead++
stackUpdated = true
case "EQ":
if e.isFloat[indexOfFirstArg] && e.isFloat[indexOfFirstArg+1] {
if e.scratch[indexOfFirstArg].(float64) == e.scratch[indexOfFirstArg+1].(float64) {
result = float64(1)
} else {
result = float64(0)
}
} else if !e.isFloat[indexOfFirstArg] && !e.isFloat[indexOfFirstArg+1] {
if e.scratch[indexOfFirstArg].(string) == e.scratch[indexOfFirstArg+1].(string) {
result = float64(1)
} else {
cannotSimplify = true
}
} else {
cannotSimplify = true
}
case "EXC":
e.scratch[indexOfFirstArg], e.scratch[indexOfFirstArg+1] = e.scratch[indexOfFirstArg+1], e.scratch[indexOfFirstArg]
e.isFloat[indexOfFirstArg], e.isFloat[indexOfFirstArg+1] = e.isFloat[indexOfFirstArg+1], e.isFloat[indexOfFirstArg]
stackUpdated = true
case "EXP":
result = math.Exp(e.scratch[indexOfFirstArg].(float64))
case "FLOOR":
result = math.Floor(e.scratch[indexOfFirstArg].(float64))
case "GE":
if e.isFloat[indexOfFirstArg] && e.isFloat[indexOfFirstArg+1] {
if math.IsNaN(e.scratch[indexOfFirstArg].(float64)) {
result = math.NaN()
} else if math.IsNaN(e.scratch[indexOfFirstArg+1].(float64)) {
result = math.NaN()
} else if e.scratch[indexOfFirstArg].(float64) >= e.scratch[indexOfFirstArg+1].(float64) {
result = float64(1)
} else {
result = float64(0)
}
} else if !e.isFloat[indexOfFirstArg] && !e.isFloat[indexOfFirstArg+1] {
if e.scratch[indexOfFirstArg].(string) == e.scratch[indexOfFirstArg+1].(string) {
result = float64(1)
} else {
cannotSimplify = true
}
} else {
cannotSimplify = true
}
case "GT":
if e.isFloat[indexOfFirstArg] && e.isFloat[indexOfFirstArg+1] {
if math.IsNaN(e.scratch[indexOfFirstArg].(float64)) {
result = math.NaN()
} else if math.IsNaN(e.scratch[indexOfFirstArg+1].(float64)) {
result = math.NaN()
} else if e.scratch[indexOfFirstArg].(float64) > e.scratch[indexOfFirstArg+1].(float64) {
result = float64(1)
} else {
result = float64(0)
}
} else if !e.isFloat[indexOfFirstArg] && !e.isFloat[indexOfFirstArg+1] {
if e.scratch[indexOfFirstArg].(string) == e.scratch[indexOfFirstArg+1].(string) {
result = float64(0)
} else {
cannotSimplify = true
}
} else {
cannotSimplify = true
}
case "IF":
// A,B,C,IF ==> A ? B : C
if e.isFloat[indexOfFirstArg] {
if e.scratch[indexOfFirstArg].(float64) < 0 || e.scratch[indexOfFirstArg].(float64) > 0 {
result = e.scratch[indexOfFirstArg+1]
} else {
result = e.scratch[indexOfFirstArg+2]
}
} else {
cannotSimplify = true
}
case "INDEX":
if math.IsNaN(e.scratch[indexOfFirstArg].(float64)) || math.IsInf(e.scratch[indexOfFirstArg].(float64), 1) || math.IsInf(e.scratch[indexOfFirstArg].(float64), -1) || e.scratch[indexOfFirstArg].(float64) <= 0 {
return newErrSyntax("%s operator requires positive finite integer: %v", token, e.scratch[indexOfFirstArg])
}
additionalArgumentCount = int(e.scratch[indexOfFirstArg].(float64))
if additionalArgumentCount > e.scratchHead-1 {
return newErrSyntax("%s operand requires %d items, but only %d on stack", token, additionalArgumentCount, e.scratchHead-1)
}
for argIdx = indexOfFirstArg - additionalArgumentCount; argIdx < indexOfFirstArg; argIdx++ {
if !e.isFloat[argIdx] {
if _, ok = arity[e.scratch[argIdx].(string)]; ok {
cannotSimplify = true
break
}
}
}
if !cannotSimplify {
e.scratch[e.scratchHead-1] = e.scratch[e.scratchHead-additionalArgumentCount-1]
e.isFloat[e.scratchHead-1] = e.isFloat[e.scratchHead-additionalArgumentCount-1]
stackUpdated = true
}
case "ISINF":
if math.IsInf(e.scratch[indexOfFirstArg].(float64), 1) || math.IsInf(e.scratch[indexOfFirstArg].(float64), -1) {
result = float64(1)
} else {
result = float64(0)
}
case "LE":
if e.isFloat[indexOfFirstArg] && e.isFloat[indexOfFirstArg+1] {
if math.IsNaN(e.scratch[indexOfFirstArg].(float64)) {
result = math.NaN()
} else if math.IsNaN(e.scratch[indexOfFirstArg+1].(float64)) {
result = math.NaN()
} else if e.scratch[indexOfFirstArg].(float64) <= e.scratch[indexOfFirstArg+1].(float64) {
result = float64(1)
} else {
result = float64(0)
}
} else if !e.isFloat[indexOfFirstArg] && !e.isFloat[indexOfFirstArg+1] {
if e.scratch[indexOfFirstArg].(string) == e.scratch[indexOfFirstArg+1].(string) {
result = float64(1)
} else {
cannotSimplify = true
}
} else {
cannotSimplify = true
}
case "LIMIT":
if math.IsNaN(e.scratch[indexOfFirstArg].(float64)) || math.IsNaN(e.scratch[indexOfFirstArg+1].(float64)) || math.IsNaN(e.scratch[indexOfFirstArg+2].(float64)) {
result = math.NaN()
} else if math.IsInf(e.scratch[indexOfFirstArg].(float64), -1) || math.IsInf(e.scratch[indexOfFirstArg+1].(float64), -1) || math.IsInf(e.scratch[indexOfFirstArg+2].(float64), -1) {
result = math.NaN()
} else if !(e.scratch[indexOfFirstArg].(float64) < e.scratch[indexOfFirstArg+1].(float64) || e.scratch[indexOfFirstArg].(float64) > e.scratch[indexOfFirstArg+2].(float64)) {
result = e.scratch[indexOfFirstArg]
} else {
result = math.NaN()
}
case "LOG":
result = math.Log(e.scratch[indexOfFirstArg].(float64))
case "LT":
if e.isFloat[indexOfFirstArg] && e.isFloat[indexOfFirstArg+1] {
if math.IsNaN(e.scratch[indexOfFirstArg].(float64)) {