forked from tyler-sommer/stick
/
exec.go
553 lines (521 loc) · 13 KB
/
exec.go
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package stick
import (
"errors"
"io"
"math"
"strconv"
"strings"
"regexp"
"fmt"
"bytes"
"github.com/tyler-sommer/stick/parse"
)
// Type state represents the internal state of a template execution.
type state struct {
out io.Writer
node parse.Node
blocks []map[string]*parse.BlockNode
env *Env
scope *scopeStack
}
type scopeStack struct {
scopes []map[string]Value
}
func (s *scopeStack) push() {
s.scopes = append(s.scopes, make(map[string]Value))
}
func (s *scopeStack) pop() {
s.scopes = s.scopes[0 : len(s.scopes)-1]
}
func (s *scopeStack) all() map[string]Value {
res := make(map[string]Value)
for _, scope := range s.scopes {
for k, v := range scope {
res[k] = v
}
}
return res
}
func (s *scopeStack) get(name string) (Value, bool) {
for i := len(s.scopes); i > 0; i-- {
scope := s.scopes[i-1]
if v, ok := scope[name]; ok {
return v, true
}
}
return nil, false
}
func (s *scopeStack) set(name string, val Value) {
for _, scope := range s.scopes {
if _, ok := scope[name]; ok {
scope[name] = val
return
}
}
s.scopes[len(s.scopes)-1][name] = val
}
// Function newState creates a new template execution state, ready for use.
func newState(out io.Writer, ctx map[string]Value, env *Env) *state {
return &state{out, nil, make([]map[string]*parse.BlockNode, 0), env, &scopeStack{[]map[string]Value{ctx}}}
}
// Method load attempts to load and parse the given template.
func (s *state) load(name string) (*parse.Tree, error) {
cnt, err := s.env.Loader.Load(name)
if err != nil {
return nil, err
}
tree := parse.NewTree(name, cnt)
err = tree.Parse()
if err != nil {
return nil, err
}
return tree, nil
}
// Method getBlock iterates through each set of blocks, returning the first
// block it encounters.
func (s *state) getBlock(name string) *parse.BlockNode {
for _, blocks := range s.blocks {
if block, ok := blocks[name]; ok {
return block
}
}
return nil
}
// Enter is called when the given Node is entered.
func (s *state) enter(node parse.Node) {
s.node = node
for _, v := range s.env.Visitors {
v.Enter(node)
}
}
// Leave is called just before the state exits the given Node.
func (s *state) leave(node parse.Node) {
for _, v := range s.env.Visitors {
v.Leave(node)
}
}
// Method walk is the main entry-point into template execution.
func (s *state) walk(node parse.Node) error {
s.enter(node)
defer s.leave(node)
switch node := node.(type) {
case *parse.ModuleNode:
if p := node.Parent(); p != nil {
tplName, err := s.evalExpr(p.TemplateRef())
if err != nil {
return err
}
tree, err := s.load(CoerceString(tplName))
if err != nil {
return err
}
s.blocks = append(s.blocks, tree.Blocks())
err = s.walkChild(node.BodyNode)
if err != nil {
return err
}
return s.walk(tree.Root())
}
return s.walk(node.BodyNode)
case *parse.BodyNode:
for _, c := range node.Children() {
err := s.walk(c)
if err != nil {
return err
}
}
case *parse.TextNode:
io.WriteString(s.out, node.Text())
case *parse.PrintNode:
v, err := s.evalExpr(node.Expr())
if err != nil {
return err
}
io.WriteString(s.out, CoerceString(v))
case *parse.BlockNode:
name := node.Name()
if block := s.getBlock(name); block != nil {
return s.walk(block.Body())
}
// TODO: It seems this should never occur.
return errors.New("Unable to locate block " + name)
case *parse.IfNode:
v, err := s.evalExpr(node.Cond())
if err != nil {
return err
}
if CoerceBool(v) {
s.walk(node.Body())
} else {
s.walk(node.Else())
}
case *parse.IncludeNode:
tpl, ctx, err := s.walkIncludeNode(node)
if err != nil {
return err
}
err = execute(tpl, s.out, ctx, s.env)
if err != nil {
return err
}
case *parse.EmbedNode:
tpl, ctx, err := s.walkIncludeNode(node.IncludeNode)
if err != nil {
return err
}
// TODO: We duplicate most of the "execute" function here.
si := newState(s.out, ctx, s.env)
tree, err := s.load(tpl)
if err != nil {
return err
}
si.blocks = append(s.blocks, node.Blocks(), tree.Blocks())
err = si.walk(tree.Root())
if err != nil {
return err
}
case *parse.UseNode:
return s.walkUseNode(node)
case *parse.ForNode:
return s.walkForNode(node)
default:
return errors.New("Unknown node " + node.String())
}
return nil
}
// walkChild only executes a subset of nodes, intended to be used on child templates.
func (s *state) walkChild(node parse.Node) error {
s.enter(node)
defer s.leave(node)
switch node := node.(type) {
case *parse.BodyNode:
for _, c := range node.Children() {
err := s.walkChild(c)
if err != nil {
return err
}
}
case *parse.UseNode:
return s.walkUseNode(node)
}
return nil
}
func (s *state) walkForNode(node *parse.ForNode) error {
res, err := s.evalExpr(node.Expr())
if err != nil {
return err
}
kn := node.Key()
vn := node.Val()
ct, err := iterate(res, func(k Value, v Value, l loop) (bool, error) {
s.scope.push()
defer s.scope.pop()
if kn != "" {
s.scope.set(kn, k)
}
s.scope.set(vn, v)
s.scope.set("loop", l)
err := s.walk(node.Body())
if err != nil {
return true, err
}
return false, nil
})
if err != nil {
return err
}
if ct == 0 {
return s.walk(node.Else())
}
return nil
}
// Method walkInclude determines the necessary parameters for including or embedding a template.
func (s *state) walkIncludeNode(node *parse.IncludeNode) (tpl string, ctx map[string]Value, err error) {
ctx = make(map[string]Value)
v, err := s.evalExpr(node.Tpl())
if err != nil {
return "", nil, err
}
tpl = CoerceString(v)
var with Value
if n := node.With(); n != nil {
with, err = s.evalExpr(n)
// TODO: Assert "with" is a hash?
if err != nil {
return "", nil, err
}
}
if !node.Only() {
ctx = s.scope.all()
}
if with != nil {
if with, ok := with.(map[string]Value); ok {
for k, v := range with {
ctx[k] = v
}
}
}
return tpl, ctx, err
}
func (s *state) walkUseNode(node *parse.UseNode) error {
v, err := s.evalExpr(node.Tpl())
if err != nil {
return err
}
tpl := CoerceString(v)
tree, err := s.load(tpl)
if err != nil {
return err
}
blocks := tree.Blocks()
for orig, alias := range node.Aliases() {
v, ok := blocks[orig]
if !ok {
return errors.New("Unable to locate block with name \"" + orig + "\"")
}
blocks[alias] = v
}
l := len(s.blocks)
lb := s.blocks[l-1]
s.blocks = append(append(s.blocks[:l-1], blocks), lb)
return nil
}
// Method evalExpr evaluates the given expression, returning a Value or error.
func (s *state) evalExpr(exp parse.Expr) (v Value, e error) {
switch exp := exp.(type) {
case *parse.NullExpr:
return nil, nil
case *parse.BoolExpr:
return exp.Value(), nil
case *parse.NameExpr:
if val, ok := s.scope.get(exp.Name()); ok {
v = val
} else {
e = errors.New("Undefined variable \"" + exp.Name() + "\"")
}
case *parse.NumberExpr:
num, err := strconv.ParseFloat(exp.Value(), 64)
if err != nil {
return nil, err
}
return num, nil
case *parse.StringExpr:
return exp.Value(), nil
case *parse.GroupExpr:
return s.evalExpr(exp.Inner())
case *parse.UnaryExpr:
in, err := s.evalExpr(exp.Expr())
if err != nil {
return nil, err
}
switch exp.Op() {
case parse.OpUnaryNot:
return !CoerceBool(in), nil
case parse.OpUnaryPositive:
// no-op, +1 = 1, +(-1) = -1, +(false) = 0
return CoerceNumber(in), nil
case parse.OpUnaryNegative:
return -CoerceNumber(in), nil
}
case *parse.BinaryExpr:
left, err := s.evalExpr(exp.Left())
if err != nil {
return nil, err
}
right, err := s.evalExpr(exp.Right())
if err != nil {
return nil, err
}
switch exp.Op() {
case parse.OpBinaryAdd:
return CoerceNumber(left) + CoerceNumber(right), nil
case parse.OpBinarySubtract:
return CoerceNumber(left) - CoerceNumber(right), nil
case parse.OpBinaryMultiply:
return CoerceNumber(left) * CoerceNumber(right), nil
case parse.OpBinaryDivide:
return CoerceNumber(left) / CoerceNumber(right), nil
case parse.OpBinaryFloorDiv:
return math.Floor(CoerceNumber(left) / CoerceNumber(right)), nil
case parse.OpBinaryModulo:
return float64(int(CoerceNumber(left)) % int(CoerceNumber(right))), nil
case parse.OpBinaryPower:
return math.Pow(CoerceNumber(left), CoerceNumber(right)), nil
case parse.OpBinaryConcat:
return CoerceString(left) + CoerceString(right), nil
case parse.OpBinaryEndsWith:
return strings.HasSuffix(CoerceString(left), CoerceString(right)), nil
case parse.OpBinaryStartsWith:
return strings.HasPrefix(CoerceString(left), CoerceString(right)), nil
case parse.OpBinaryIn:
return contains(right, left)
case parse.OpBinaryNotIn:
res, err := contains(right, left)
if err != nil {
return false, err
}
return !res, nil
case parse.OpBinaryIs:
if fn, ok := right.(func(v Value) bool); ok {
return fn(left), nil
}
return nil, errors.New("right operand was of unexpected type")
case parse.OpBinaryIsNot:
if fn, ok := right.(func(v Value) bool); ok {
return !fn(left), nil
}
return nil, errors.New("right operand was of unexpected type")
case parse.OpBinaryMatches:
reg, err := regexp.Compile(CoerceString(right))
if err != nil {
return nil, err
}
return reg.MatchString(CoerceString(left)), nil
case parse.OpBinaryEqual:
return equal(left, right), nil
case parse.OpBinaryNotEqual:
return !equal(left, right), nil
case parse.OpBinaryGreaterEqual:
return CoerceNumber(left) >= CoerceNumber(right), nil
case parse.OpBinaryGreaterThan:
return CoerceNumber(left) > CoerceNumber(right), nil
case parse.OpBinaryLessEqual:
return CoerceNumber(left) <= CoerceNumber(right), nil
case parse.OpBinaryLessThan:
return CoerceNumber(left) < CoerceNumber(right), nil
case parse.OpBinaryRange:
l, r := CoerceNumber(left), CoerceNumber(right)
res := make([]float64, uint(math.Ceil(r-l))+1)
for i, k := 0, l; k <= r; i, k = i+1, k+1 {
res[i] = k
}
return res, nil
case parse.OpBinaryBitwiseAnd:
return int(CoerceNumber(left)) & int(CoerceNumber(right)), nil
case parse.OpBinaryBitwiseOr:
return int(CoerceNumber(left)) | int(CoerceNumber(right)), nil
case parse.OpBinaryBitwiseXor:
return int(CoerceNumber(left)) ^ int(CoerceNumber(right)), nil
case parse.OpBinaryAnd:
return CoerceBool(left) && CoerceBool(right), nil
case parse.OpBinaryOr:
return CoerceBool(left) && CoerceBool(right), nil
}
case *parse.FuncExpr:
return s.evalFunction(exp)
case *parse.FilterExpr:
return s.evalFilter(exp)
case *parse.GetAttrExpr:
c, err := s.evalExpr(exp.Cont())
if err != nil {
return nil, err
}
k, err := s.evalExpr(exp.Attr())
if err != nil {
return nil, err
}
exargs := exp.Args()
args := make([]Value, len(exargs))
for k, e := range exargs {
v, err := s.evalExpr(e)
if err != nil {
return nil, err
}
args[k] = v
}
v, err = GetAttr(c, CoerceString(k), args...)
if err != nil {
return nil, err
}
case *parse.TestExpr:
if tfn, ok := s.env.Tests[exp.Name()]; ok {
eargs := exp.Args()
args := make([]Value, len(eargs))
for i, e := range eargs {
v, err := s.evalExpr(e)
if err != nil {
return nil, err
}
args[i] = v
}
return func(v Value) bool {
return tfn(s.env, v, args...)
}, nil
}
return nil, fmt.Errorf(`unknown test "%v"`, exp.Name())
}
return v, nil
}
func (s *state) evalFunction(exp *parse.FuncExpr) (v Value, e error) {
fnName := exp.Name()
switch fnName {
case "block":
eargs := exp.Args()
if len(eargs) != 1 {
return nil, errors.New("block expects one parameter")
}
val, err := s.evalExpr(eargs[0])
if err != nil {
return nil, err
}
name := CoerceString(val)
if blk := s.getBlock(name); blk != nil {
pout := s.out
buf := &bytes.Buffer{}
s.out = buf
err = s.walk(blk.Body())
if err != nil {
return nil, err
}
s.out = pout
return buf.String(), nil
}
return nil, errors.New("Unable to locate block \"" + name + "\"")
}
if fn, ok := s.env.Functions[fnName]; ok {
eargs := exp.Args()
args := make([]Value, len(eargs))
for i, e := range eargs {
v, err := s.evalExpr(e)
if err != nil {
return nil, err
}
args[i] = v
}
return fn(s.env, args...), nil
}
return nil, errors.New("Undeclared function \"" + fnName + "\"")
}
func (s *state) evalFilter(exp *parse.FilterExpr) (v Value, e error) {
ftName := exp.Name()
if fn, ok := s.env.Filters[ftName]; ok {
eargs := exp.Args()
if len(eargs) == 0 {
return nil, errors.New("Filter call must receive at least one argument")
}
args := make([]Value, len(eargs))
for i, e := range eargs {
v, err := s.evalExpr(e)
if err != nil {
return nil, err
}
args[i] = v
}
return fn(s.env, args[0], args[1:]...), nil
}
return nil, errors.New("Undeclared filter \"" + ftName + "\"")
}
// execute kicks off execution of the given template.
func execute(name string, out io.Writer, ctx map[string]Value, env *Env) error {
s := newState(out, ctx, env)
tree, err := s.load(name)
if err != nil {
return err
}
s.blocks = append(s.blocks, tree.Blocks())
err = s.walk(tree.Root())
if err != nil {
return err
}
return nil
}