apex/up

// Package ast provides the log query language abstract syntax tree.
package ast

import (
    "fmt"
    "strconv"
    "strings"
)

// Op type.
type Op string

// Op types.
const (
    LNOT Op = "not"
    NOT     = "!"
    IN      = "in"
    OR      = "||"
    AND     = "&&"
    NE      = "!="
    EQ      = "="
    GT      = ">"
    LT      = "<"
    GE      = ">="
    LE      = "<="
)

// Node interface.
type Node interface {
    String() string
}

// Root node.
type Root struct {
    Node Node
}

// String implementation.
func (n Root) String() string {
    return fmt.Sprintf(`{ %s }`, n.Node)
}

// Expr node.
type Expr struct {
    Node Node
}

// String implementation.
func (n Expr) String() string {
    return fmt.Sprintf(`(%s)`, n.Node)
}

// Literal node.
type Literal string

// String implementation.
func (n Literal) String() string {
    return fmt.Sprintf(`%s`, string(n))
}

// Tuple node.
type Tuple []Node

// String implementation.
func (n Tuple) String() string {
    return fmt.Sprintf(`%#v`, n)
}

// Contains node.
type Contains struct {
    Node Node
}

// String implementation.
func (n Contains) String() string {
    switch v := n.Node.(type) {
    case String:
        return fmt.Sprintf(`"*%s*"`, string(v))
    default:
        return fmt.Sprintf(`%s`, n.Node)
    }
}

// String node.
type String string

// String implementation.
func (n String) String() string {
    return fmt.Sprintf(`$.message = %q`, string(n))
}

// Property node.
type Property string

// String implementation.
func (n Property) String() string {
    return fmt.Sprintf(`$.%s`, string(n))
}

// Field node.
type Field string

// String implementation.
func (n Field) String() string {
    return fmt.Sprintf(`$.fields.%s`, string(n))
}

// Subscript node.
type Subscript struct {
    Left  Node
    Right Node
}

// String implementation.
func (n Subscript) String() string {
    return fmt.Sprintf(`%s[%s]`, n.Left, n.Right)
}

// Member node.
type Member struct {
    Left  Node
    Right Node
}

// String implementation.
func (n Member) String() string {
    return fmt.Sprintf(`%s.%s`, n.Left, n.Right)
}

// Number node.
type Number struct {
    Value float64
    Unit  string
}

// String implementation.
func (n Number) String() string {
    v := n.Value

    switch n.Unit {
    case "kb":
        v *= 1 << 10
    case "mb":
        v *= 1 << 20
    case "gb":
        v *= 1 << 30
    case "s":
        v *= 1000
    }

    return strconv.FormatFloat(v, 'f', -1, 64)
}

// Binary node.
type Binary struct {
    Op    Op
    Left  Node
    Right Node
}

// String implementation.
func (n Binary) String() string {
    switch n.Op {
    case IN:
        var s []string
        for _, v := range n.Right.(Tuple) {
            s = append(s, fmt.Sprintf(`%s %s %s`, n.Left, EQ, value(v)))
        }
        return fmt.Sprintf(`(%s)`, strings.Join(s, " || "))
    case EQ, NE, GT, LT, GE, LE:
        return fmt.Sprintf(`%s %s %s`, n.Left, n.Op, value(n.Right))
    default:
        return fmt.Sprintf(`%s %s %s`, n.Left, n.Op, n.Right)
    }
}

// Unary node.
type Unary struct {
    Op    Op
    Right Node
}

// String implementation.
func (n Unary) String() string {
    switch n.Op {
    case LNOT:
        return fmt.Sprintf(`!(%s)`, n.Right)
    default:
        return fmt.Sprintf(`%s%s`, n.Op, n.Right)
    }
}

// value from node.
func value(n Node) string {
    switch v := n.(type) {
    case String:
        return fmt.Sprintf("%q", string(v))
    case Field:
        return fmt.Sprintf("%q", string(v))
    default:
        return n.String()
    }
}