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compiler.go
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compiler.go
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package eval
//go:generate ./boilerplate.py
import (
"fmt"
"strconv"
"github.com/elves/elvish/parse"
"github.com/elves/elvish/util"
)
type scope map[string]bool
// compiler maintains the set of states needed when compiling a single source
// file.
type compiler struct {
// Builtin scope.
builtin scope
// Lexical scopes.
scopes []scope
// Variables captured from outer scopes.
capture scope
// Position of what is being compiled.
begin, end int
// Information about the source.
name, text string
}
func compile(b, g scope, n *parse.Chunk, name, text string) (op Op, err error) {
cp := &compiler{b, []scope{g}, scope{}, 0, 0, name, text}
defer util.Catch(&err)
return cp.chunkOp(n), nil
}
func (cp *compiler) compiling(n parse.Node) {
cp.begin, cp.end = n.Begin(), n.End()
}
func (cp *compiler) errorpf(begin, end int, format string, args ...interface{}) {
throw(&CompilationError{fmt.Sprintf(format, args...),
util.SourceContext{cp.name, cp.text, begin, end, nil}})
}
func (cp *compiler) errorf(format string, args ...interface{}) {
cp.errorpf(cp.begin, cp.end, format, args...)
}
func (cp *compiler) thisScope() scope {
return cp.scopes[len(cp.scopes)-1]
}
func (cp *compiler) pushScope() scope {
sc := scope{}
cp.scopes = append(cp.scopes, sc)
return sc
}
func (cp *compiler) popScope() {
cp.scopes[len(cp.scopes)-1] = nil
cp.scopes = cp.scopes[:len(cp.scopes)-1]
}
func (cp *compiler) registerVariableGet(qname string) bool {
_, ns, name := ParseAndFixVariable(qname)
if ns != "" && ns != "local" && ns != "up" {
// Variable in another mod, do nothing
return true
}
_, err := strconv.Atoi(name)
isnum := err == nil
// Find in local scope
if ns == "" || ns == "local" {
if cp.thisScope()[name] || isnum {
return true
}
}
// Find in upper scopes
if ns == "" || ns == "up" {
for i := len(cp.scopes) - 2; i >= 0; i-- {
if cp.scopes[i][name] || isnum {
// Existing name: record capture and return.
cp.capture[name] = true
return true
}
}
}
// Find in builtin scope
if ns == "" || ns == "builtin" {
_, ok := cp.builtin[name]
if ok {
return true
}
}
return false
}
func (cp *compiler) registerVariableSet(qname string) bool {
_, ns, name := ParseAndFixVariable(qname)
switch ns {
case "local":
cp.thisScope()[name] = true
return true
case "up":
for i := len(cp.scopes) - 2; i >= 0; i-- {
if cp.scopes[i][name] {
// Existing name: record capture and return.
cp.capture[name] = true
return true
}
}
return false
case "builtin":
cp.errorf("cannot set builtin variable")
return false
case "":
if cp.thisScope()[name] {
// A name on current scope. Do nothing.
return true
}
// Walk up the upper scopes
for i := len(cp.scopes) - 2; i >= 0; i-- {
if cp.scopes[i][name] {
// Existing name. Do nothing
cp.capture[name] = true
return true
}
}
// New name. Register on this scope!
cp.thisScope()[name] = true
return true
default:
// Variable in another mod, do nothing
return true
}
}