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|
package scl
import (
"fmt"
"unicode"
)
type variable struct {
name string
value string
}
type mixin struct {
declaration *scannerLine
arguments []variable
defaults []string
}
type scope struct {
parent *scope
branch *scannerLine
branchScope *scope
variables map[string]*variable
mixins map[string]*mixin
}
func newScope() *scope {
return &scope{
variables: make(map[string]*variable),
mixins: make(map[string]*mixin),
}
}
func (s *scope) setArgumentVariable(name, value string) {
s.variables[name] = &variable{name, value}
}
func (s *scope) setVariable(name, value string) {
v, ok := s.variables[name]
if !ok || v == nil {
s.variables[name] = &variable{name, value}
} else {
s.variables[name].value = value
}
}
func (s *scope) variable(name string) string {
value, ok := s.variables[name]
if !ok || value == nil {
return ""
}
return s.variables[name].value
}
func (s *scope) setMixin(name string, declaration *scannerLine, argumentTokens []token, defaults []string) {
mixin := &mixin{
declaration: declaration,
defaults: defaults,
}
for _, t := range argumentTokens {
mixin.arguments = append(mixin.arguments, variable{name: t.content})
}
s.mixins[name] = mixin
}
func (s *scope) removeMixin(name string) {
delete(s.mixins, name)
}
func (s *scope) mixin(name string) (*mixin, error) {
m, ok := s.mixins[name]
if !ok {
return nil, fmt.Errorf("Mixin %s not declared in this scope", name)
}
return m, nil
}
func (s *scope) interpolateLiteral(literal string) (outp string, err error) {
isVariableChar := func(c rune) bool {
return unicode.IsLetter(c) || unicode.IsDigit(c) || c == '_'
}
unknownVariable := func(name []byte) {
err = fmt.Errorf("Unknown variable '$%s'", name)
}
unfinishedVariable := func(name []byte) {
err = fmt.Errorf("Expecting closing right brace in variable ${%s}", name)
}
result := func() (result []byte) {
var (
backSlash = '\\'
dollar = '$'
leftBrace = '{'
rightBrace = '}'
backtick = '`'
slashEscaped = false
variableStarted = false
variableIsBraceEscaped = false
variable = []byte{}
literalStarted = false
)
for _, c := range []byte(literal) {
if literalStarted {
if rune(c) == backtick {
literalStarted = false
continue
}
result = append(result, c)
continue
}
if variableStarted {
if len(variable) == 0 {
// If the first character is a dollar, then this
// is a $$var escape
if rune(c) == dollar {
variableStarted = false
variableIsBraceEscaped = false
// Write out two dollars – one for the skipped var
// signifier, and the current one
result = append(result, byte(dollar))
continue
}
// If the first character is a curl brace,
// it's the start of a ${var} syntax
if !variableIsBraceEscaped {
if rune(c) == leftBrace {
variableIsBraceEscaped = true
continue
} else {
variableIsBraceEscaped = false
}
}
}
// If this is a valid variable character,
// add it to the variable building
if isVariableChar(rune(c)) {
variable = append(variable, c)
continue
}
// If the variable is zero length, then it's a dollar literal
if len(variable) == 0 {
variableStarted = false
variableIsBraceEscaped = false
result = append(result, byte(dollar), c)
continue
}
// Brace-escaped variables must end with a closing brace
if variableIsBraceEscaped {
if rune(c) != rightBrace {
unfinishedVariable(variable)
return
}
}
writeOutput := !variableIsBraceEscaped
// The variable has ended
variableStarted = false
variableIsBraceEscaped = false
// The variable is complete; look up its value
if replacement := s.variable(string(variable)); replacement != "" {
result = append(result, []byte(replacement)...)
if writeOutput {
result = append(result, c)
}
continue
}
unknownVariable(variable)
return
}
if slashEscaped {
result = append(result, c)
slashEscaped = false
continue
}
switch rune(c) {
case backSlash:
slashEscaped = true
continue
case dollar:
variableStarted, variable = true, []byte{}
continue
case backtick:
literalStarted = true
continue
}
result = append(result, c)
slashEscaped = false
}
if literalStarted {
err = fmt.Errorf("Unterminated backtick literal")
return
}
// If the last character is a slash, add it
if slashEscaped {
result = append(result, byte(backSlash))
}
// The string ended mid-variable, so add it if possible
if variableStarted {
if variableIsBraceEscaped {
unfinishedVariable(variable)
return
} else if replacement := s.variable(string(variable)); replacement != "" {
result = append(result, []byte(replacement)...)
} else {
unknownVariable(variable)
return
}
}
return
}()
outp = string(result)
return
}
func (s *scope) clone() *scope {
s2 := newScope()
s2.parent = s
s2.branch = s.branch
s2.branchScope = s.branchScope
for k, v := range s.variables {
s2.variables[k] = v
}
for k, v := range s.mixins {
s2.mixins[k] = v
}
return s2
}
|
