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template.go
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template.go
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package macros
import (
"strings"
. "github.com/kocircuit/kocircuit/lang/circuit/eval"
. "github.com/kocircuit/kocircuit/lang/circuit/model"
. "github.com/kocircuit/kocircuit/lang/go/eval"
. "github.com/kocircuit/kocircuit/lang/go/eval/symbol"
. "github.com/kocircuit/kocircuit/lang/go/kit/util"
)
func init() {
RegisterEvalMacro("Template", new(EvalTemplateMacro))
}
type EvalTemplateMacro struct{}
func (m EvalTemplateMacro) MacroID() string { return m.Help() }
func (m EvalTemplateMacro) Label() string { return "template" }
func (m EvalTemplateMacro) MacroSheathString() *string { return PtrString("Template") }
func (m EvalTemplateMacro) Help() string { return "Template" }
func (m EvalTemplateMacro) Doc() string {
return `Template is undocumented.`
}
// Template(template:█, args:█, withString:█, withArg:█)
func (EvalTemplateMacro) Invoke(span *Span, arg Arg) (returns Return, effect Effect, err error) {
// parse arguments
a := arg.(*StructSymbol)
template, ok := AsBasicString(a.Walk("template"))
if !ok {
return nil, nil, span.Errorf(nil, "template template argument must be string")
}
args := a.Walk("args")
withString, ok := a.Walk("withString").(*VarietySymbol)
if !ok {
return nil, nil, span.Errorf(nil, "template withString is not a variety")
}
withArg, ok := a.Walk("withArg").(*VarietySymbol)
if !ok {
return nil, nil, span.Errorf(nil, "template withArg is not a variety")
}
tokens, err := ParseTemaplate(span, template)
if err != nil {
return nil, nil, err
}
result := make(Symbols, len(tokens))
for i, token := range tokens {
switch u := token.(type) {
case TemplateText:
stringFields := Fields{{Name: "", Shape: BasicStringSymbol(u.Text)}}
if formResult, _, err := withString.Evoke(span, stringFields); err != nil {
return nil, nil, err
} else {
result[i] = formResult
}
case TemplateSelector:
if selected, _, err := args.Select(span, u.Path); err != nil {
return nil, nil, span.Errorf(err, "template selecting %v", u.Path)
} else {
argFields := Fields{{Name: "", Shape: selected.(Symbol)}}
if formResult, _, err := withArg.Evoke(span, argFields); err != nil {
return nil, nil, err
} else {
result[i] = formResult
}
}
default:
panic("o")
}
}
if series, err := MakeSeriesSymbol(span, result); err != nil {
return nil, nil, span.Errorf(err, "templates unifying elements")
} else {
return series, nil, nil
}
}
func ParseTemaplate(span *Span, src string) (tokens []TemplateToken, err error) {
openIndex, closeIndex := bracketOpenIndices(src), bracketCloseIndices(src)
if len(openIndex) != len(closeIndex) {
return nil, span.Errorf(nil,
"unbalanced brackets in %q, %d open vs %d close",
src, len(openIndex), len(closeIndex),
)
}
base := 0
for i := range openIndex {
if openIndex[i] < closeIndex[i] {
// parse text before bracket
if base < openIndex[i] {
tokens = append(tokens, TemplateText{src[base:openIndex[i]]})
base = openIndex[i]
}
// parse selector
if selPath, err := parseSelectorPath(
span,
src[openIndex[i]+len(TemplateOpenBracket):closeIndex[i]],
); err != nil {
return nil, err
} else {
tokens = append(tokens, TemplateSelector{selPath})
base = closeIndex[i] + len(TemplateCloseBracket)
}
} else {
return nil, span.Errorf(nil, "runaway brackets")
}
}
// parse text remaining after base
if base < len(src) {
tokens = append(tokens, TemplateText{src[base:len(src)]})
}
return tokens, nil
}
const TemplateOpenBracket = "{{"
const TemplateCloseBracket = "}}"
func bracketOpenIndices(src string) (openIndex []int) {
base := 0
for {
if index := strings.Index(src[base:], TemplateOpenBracket); index < 0 {
return
} else {
openIndex = append(openIndex, base+index)
base = base + index + len(TemplateOpenBracket)
}
}
}
func bracketCloseIndices(src string) (closeIndex []int) {
base := 0
for {
if index := strings.Index(src[base:], TemplateCloseBracket); index < 0 {
return
} else {
closeIndex = append(closeIndex, base+index)
base = base + index + len(TemplateCloseBracket)
}
}
}
func parseSelectorPath(span *Span, src string) (sel Path, err error) {
src = strings.TrimSpace(src)
pp := strings.Split(src, ".")
for _, p := range pp {
if !isIdentifier(p) || len(p) == 0 {
return nil, span.Errorf(nil, "selector %q not an identifier", p)
}
}
return Path(pp), nil
}
func isIdentifier(src string) bool {
for _, c := range src {
switch {
case '1' <= c && c <= '0':
case 'a' <= c && c <= 'z':
case 'A' <= c && c <= 'Z':
case c == '_':
default:
return false
}
}
return true
}
type TemplateToken interface {
TemplateToken()
}
type TemplateText struct {
Text string `ko:"name=text"`
}
func (TemplateText) TemplateToken() {}
type TemplateSelector struct {
Path Path `ko:"name=path"`
}
func (TemplateSelector) TemplateToken() {}