mirror of
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127 lines
3.3 KiB
Go
127 lines
3.3 KiB
Go
package eval
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import (
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"fmt"
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"io"
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"github.com/elves/elvish/pkg/diag"
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"github.com/elves/elvish/pkg/eval/vars"
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"github.com/elves/elvish/pkg/parse"
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)
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// compiler maintains the set of states needed when compiling a single source
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// file.
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type compiler struct {
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// Builtin namespace.
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builtin *staticNs
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// Lexical namespaces.
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scopes []*staticNs
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// Sources of captured variables.
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captures []*staticUpNs
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// Destination of warning messages. This is currently only used for
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// deprecation messages.
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warn io.Writer
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// Deprecation registry.
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deprecations deprecationRegistry
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// Information about the source.
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srcMeta parse.Source
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}
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type capture struct {
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name string
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// If true, the captured variable is from the immediate outer level scope,
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// i.e. the local scope the lambda is evaluated in. Otherwise the captured
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// variable is from a more outer level, i.e. the upvalue scope the lambda is
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// evaluated in.
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local bool
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// Index to the captured variable.
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index int
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}
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func compile(b, g *staticNs, tree parse.Tree, w io.Writer) (op nsOp, err error) {
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g = g.clone()
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cp := &compiler{
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b, []*staticNs{g}, []*staticUpNs{new(staticUpNs)},
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w, newDeprecationRegistry(), tree.Source}
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defer func() {
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r := recover()
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if r == nil {
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return
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} else if e := GetCompilationError(r); e != nil {
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// Save the compilation error and stop the panic.
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err = e
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} else {
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// Resume the panic; it is not supposed to be handled here.
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panic(r)
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}
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}()
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chunkOp := cp.chunkOp(tree.Root)
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return nsOp{chunkOp, g}, nil
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}
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type nsOp struct {
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inner effectOp
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template *staticNs
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}
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// Prepares a new local namespace before executing the inner effectOp. Replaces
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// fm.local.
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func (op nsOp) exec(fm *Frame) Exception {
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op.prepareNs(fm)
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return op.inner.exec(fm)
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}
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func (op nsOp) prepareNs(fm *Frame) {
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if len(op.template.names) > len(fm.local.names) {
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n := len(op.template.names)
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newLocal := &Ns{make([]vars.Var, n), op.template.names, op.template.deleted}
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copy(newLocal.slots, fm.local.slots)
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for i := len(fm.local.names); i < n; i++ {
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newLocal.slots[i] = MakeVarFromName(newLocal.names[i])
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}
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fm.local = newLocal
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} else {
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// If no new has been created, there might still be some existing
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// variables deleted.
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fm.local = &Ns{fm.local.slots, fm.local.names, op.template.deleted}
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}
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}
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const compilationErrorType = "compilation error"
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func (cp *compiler) errorpf(r diag.Ranger, format string, args ...interface{}) {
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// The panic is caught by the recover in compile above.
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panic(&diag.Error{
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Type: compilationErrorType,
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Message: fmt.Sprintf(format, args...),
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Context: *diag.NewContext(cp.srcMeta.Name, cp.srcMeta.Code, r)})
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}
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// GetCompilationError returns a *diag.Error if the given value is a compilation
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// error. Otherwise it returns nil.
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func GetCompilationError(e interface{}) *diag.Error {
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if e, ok := e.(*diag.Error); ok && e.Type == compilationErrorType {
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return e
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}
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return nil
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}
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func (cp *compiler) thisScope() *staticNs {
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return cp.scopes[len(cp.scopes)-1]
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}
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func (cp *compiler) pushScope() (*staticNs, *staticUpNs) {
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sc := new(staticNs)
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up := new(staticUpNs)
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cp.scopes = append(cp.scopes, sc)
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cp.captures = append(cp.captures, up)
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return sc, up
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}
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func (cp *compiler) popScope() {
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cp.scopes[len(cp.scopes)-1] = nil
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cp.scopes = cp.scopes[:len(cp.scopes)-1]
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cp.captures[len(cp.captures)-1] = nil
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cp.captures = cp.captures[:len(cp.captures)-1]
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}
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