// noOp is the dual of noVar. It also checks for assignment to builtins.
// It just errors out if there is a conflict.
func (c *Context) noOp(name string) {
if name == "pi" || name == "e" { // Cannot redefine these.
value.Errorf("cannot reassign %q", name)
}
if c.UnaryFn[name] == nil && c.BinaryFn[name] == nil {
return
}
value.Errorf("cannot define variable %s; it is an op", name)
}
// noVar guarantees that there is no global variable with that name,
// preventing an op from being defined with the same name as a variable,
// which could cause problems. A variable with value zero is considered to
// be OK, so one can clear a variable before defining a symbol. A cleared
// variable is removed from the global symbol table.
// noVar also prevents defining builtin variables as ops.
func (c *Context) noVar(name string) {
if name == "_" || name == "pi" || name == "e" { // Cannot redefine these.
value.Errorf(`cannot define op with name %q`, name)
}
sym := c.Stack[0][name]
if sym == nil {
return
}
if i, ok := sym.(value.Int); ok && i == 0 {
delete(c.Stack[0], name)
return
}
value.Errorf("cannot define op %s; it is a variable (%[1]s=0 to clear)", name)
}
func (e variableExpr) Eval(context value.Context) value.Value {
v := context.Lookup(e.name)
if v == nil {
value.Errorf("undefined variable %q", e.name)
}
return v
}
func (u *unaryCall) Eval(context value.Context) value.Value {
arg := u.arg.Eval(context)
context.Push()
defer context.Pop()
exec := context.(*execContext) // Sigh.
fn := exec.unaryFn[u.name]
if fn == nil || fn.body == nil {
value.Errorf("unary %q undefined", u.name)
}
context.AssignLocal(fn.right.name, arg)
var v value.Value
for _, e := range fn.body {
v = e.Eval(context)
}
if v == nil {
value.Errorf("no value returned by %q", u.name)
}
return v
}
// EvalUnary evaluates a unary operator.
func (c *Context) EvalUnary(op string, right value.Value) value.Value {
right = right.Eval(c)
fn := c.UnaryFn[op]
if fn == nil {
return value.Unary(c, op, right)
}
if fn.Body == nil {
value.Errorf("unary %q undefined", op)
}
c.push()
defer c.pop()
c.assignLocal(fn.Right, right)
var v value.Value
for _, e := range fn.Body {
v = e.Eval(c)
}
if v == nil {
value.Errorf("no value returned by %q", op)
}
return v
}
func (s sliceExpr) Eval(context value.Context) value.Value {
v := make([]value.Value, len(s))
for i, x := range s {
elem := x.Eval(context)
// Each element must be a singleton.
if !isScalar(elem) {
value.Errorf("vector element must be scalar; have %s", elem)
}
v[i] = elem
}
return value.NewVector(v)
}
func (b *binaryCall) Eval(context value.Context) value.Value {
left := b.left.Eval(context)
right := b.right.Eval(context)
context.Push()
defer context.Pop()
exec := context.(*execContext) // Sigh.
fn := exec.binaryFn[b.name]
if fn == nil || fn.body == nil {
value.Errorf("binary %q undefined", b.name)
}
context.AssignLocal(fn.left.name, left)
context.AssignLocal(fn.right.name, right)
var v value.Value
for _, e := range fn.body {
v = e.Eval(context)
}
if v == nil {
value.Errorf("no value returned by %q", b.name)
}
return v
}
// Assign assigns the variable the value. The variable must
// be defined either in the current function or globally.
// Inside a function, new variables become locals.
func (c *Context) Assign(name string, val value.Value) {
n := len(c.Stack)
if n == 0 {
value.Errorf("empty stack; cannot happen")
}
globals := c.Stack[0]
if n > 1 {
// In this function?
frame := c.Stack[n-1]
_, globallyDefined := globals[name]
if _, ok := frame[name]; ok || !globallyDefined {
frame[name] = val
return
}
}
// Assign global variable.
c.noOp(name)
globals[name] = val
}
// put writes to out a version of the value that will recreate it when parsed.
func put(out io.Writer, val value.Value) {
switch val := val.(type) {
case value.Char:
fmt.Fprintf(out, "%q", rune(val))
case value.Int:
fmt.Fprintf(out, "%d", int(val))
case value.BigInt:
fmt.Fprintf(out, "%d", val.Int)
case value.BigRat:
fmt.Fprintf(out, "%d/%d", val.Num(), val.Denom())
case value.BigFloat:
// TODO The actual value might not have the same prec as
// the configuration, so we might not get this right
// Probably not important but it would be nice to fix it.
if val.Sign() == 0 || val.IsInf() {
// These have prec 0 and are easy.
// They shouldn't appear anyway, but be safe.
fmt.Fprintf(out, "%g", val)
return
}
digits := int(float64(val.Prec()) * 0.301029995664) // 10 log 2.
fmt.Fprintf(out, "%.*g", digits, val.Float)
case value.Vector:
if val.AllChars() {
fmt.Fprintf(out, "%q", val)
return
}
for i, v := range val {
if i > 0 {
fmt.Fprint(out, " ")
}
put(out, v)
}
case value.Matrix:
put(out, val.Shape())
fmt.Fprint(out, " rho ")
put(out, val.Data())
default:
value.Errorf("internal error: can't save type %T", val)
}
}
// save writes the state of the workspace to the named file.
// The format of the output is ivy source text.
func save(c *exec.Context, file string, conf *config.Config) {
// "<conf.out>" is a special case for testing.
out := conf.Output()
if file != "<conf.out>" {
fd, err := os.Create(file)
if err != nil {
value.Errorf("%s", err)
}
defer fd.Close()
buf := bufio.NewWriter(fd)
defer buf.Flush()
out = buf
}
// Configuration settings. We will set the base below,
// after we have printed all numbers in base 10.
fmt.Fprintf(out, ")prec %d\n", conf.FloatPrec())
ibase, obase := conf.Base()
fmt.Fprintf(out, ")maxbits %d\n", conf.MaxBits())
fmt.Fprintf(out, ")maxdigits %d\n", conf.MaxDigits())
fmt.Fprintf(out, ")origin %d\n", conf.Origin())
fmt.Fprintf(out, ")prompt %q\n", conf.Prompt())
fmt.Fprintf(out, ")format %q\n", conf.Format())
// Ops.
printed := make(map[exec.OpDef]bool)
for _, def := range c.Defs {
var fn *exec.Function
if def.IsBinary {
fn = c.BinaryFn[def.Name]
} else {
fn = c.UnaryFn[def.Name]
}
for _, ref := range references(c, fn.Body) {
if !printed[ref] {
if ref.IsBinary {
fmt.Fprintf(out, "op _ %s _\n", ref.Name)
} else {
fmt.Fprintf(out, "op %s _\n", ref.Name)
}
printed[ref] = true
}
}
printed[def] = true
fmt.Fprintln(out, fn)
}
// Global variables.
syms := c.Stack[0]
if len(syms) > 0 {
// Set the base strictly to 10 for output.
fmt.Fprintf(out, "# Set base 10 for parsing numbers.\n)base 10\n")
// Sort the names for consistent output.
sorted := sortSyms(syms)
for _, sym := range sorted {
// pi and e are generated
if sym.name == "pi" || sym.name == "e" {
continue
}
fmt.Fprintf(out, "%s = ", sym.name)
put(out, sym.val)
fmt.Fprint(out, "\n")
}
}
// Now we can set the base.
fmt.Fprintf(out, ")ibase %d\n", ibase)
fmt.Fprintf(out, ")obase %d\n", obase)
}