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format.go
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format.go
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package semantic
import (
"fmt"
"strings"
)
type FormatOption func(*formatter)
// Formatted produces a Formatter object suitable for printing
// using the standard fmt package.
// Currently only works for some expressions.
func Formatted(n Node, opts ...FormatOption) fmt.Formatter {
f := formatter{
n: n,
}
for _, o := range opts {
o(&f)
}
return f
}
type formatter struct {
n Node
}
func (f formatter) Format(fs fmt.State, c rune) {
v := &formattingVisitor{}
Walk(v, f.n)
var result string
if len(v.stack) == 0 {
result = "<semantic format error, empty stack>"
} else if len(v.stack) > 1 {
var sb strings.Builder
sb.WriteString("<semantic format error, big stack:")
for _, s := range v.stack {
sb.WriteString(" " + s)
}
sb.WriteString(">")
result = sb.String()
} else {
result = v.stack[0]
}
fmt.Fprintf(fs, "%v", result)
}
type formattingVisitor struct {
stack []string
}
func (v *formattingVisitor) push(s string) {
v.stack = append(v.stack, s)
}
func (v *formattingVisitor) pop() string {
l := len(v.stack)
if l == 0 {
return "<semantic format error, pop empty>"
}
s := v.stack[l-1]
v.stack = v.stack[:l-1]
return s
}
func (v *formattingVisitor) Visit(node Node) Visitor {
switch n := node.(type) {
case *LogicalExpression:
case *BinaryExpression:
case *MemberExpression:
case *StringLiteral:
case *FloatLiteral:
case *IntegerLiteral:
case *IdentifierExpression:
default:
// Do not recurse into unknown nodes, just push an error string
// onto the stack
v.push(fmt.Sprintf("<semantic format error, unknown node %T>", n))
return nil
}
return v
}
func (v *formattingVisitor) Done(node Node) {
switch n := node.(type) {
case *LogicalExpression:
rhs := v.pop()
lhs := v.pop()
v.push(lhs + " " + n.Operator.String() + " " + rhs)
case *BinaryExpression:
rhs := v.pop()
lhs := v.pop()
v.push(lhs + " " + n.Operator.String() + " " + rhs)
case *MemberExpression:
o := v.pop()
v.push(o + "." + n.Property.Name())
case *StringLiteral:
v.push("\"" + n.Value + "\"")
case *FloatLiteral:
// %f will add zeros even for whole numbers, it's possible to easily tell
// the difference between integers and floats in output.
v.push(fmt.Sprintf("%f", n.Value))
case *IntegerLiteral:
v.push(fmt.Sprintf("%v", n.Value))
case *IdentifierExpression:
v.push(n.Name.Name())
}
}