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package compiler
import (
"fmt"
"github.com/d5/tengo/compiler/ast"
"github.com/d5/tengo/compiler/token"
)
func (c *Compiler) compileAssign(node ast.Node, lhs, rhs []ast.Expr, op token.Token) error {
numLHS, numRHS := len(lhs), len(rhs)
if numLHS > 1 || numRHS > 1 {
return c.errorf(node, "tuple assignment not allowed")
}
// resolve and compile left-hand side
ident, selectors := resolveAssignLHS(lhs[0])
numSel := len(selectors)
if op == token.Define && numSel > 0 {
// using selector on new variable does not make sense
return c.errorf(node, "operator ':=' not allowed with selector")
}
symbol, depth, exists := c.symbolTable.Resolve(ident)
if op == token.Define {
if depth == 0 && exists {
return c.errorf(node, "'%s' redeclared in this block", ident)
}
symbol = c.symbolTable.Define(ident)
} else {
if !exists {
return c.errorf(node, "unresolved reference '%s'", ident)
}
}
// +=, -=, *=, /=
if op != token.Assign && op != token.Define {
if err := c.Compile(lhs[0]); err != nil {
return err
}
}
// compile RHSs
for _, expr := range rhs {
if err := c.Compile(expr); err != nil {
return err
}
}
switch op {
case token.AddAssign:
c.emit(node, OpAdd)
case token.SubAssign:
c.emit(node, OpSub)
case token.MulAssign:
c.emit(node, OpMul)
case token.QuoAssign:
c.emit(node, OpDiv)
case token.RemAssign:
c.emit(node, OpRem)
case token.AndAssign:
c.emit(node, OpBAnd)
case token.OrAssign:
c.emit(node, OpBOr)
case token.AndNotAssign:
c.emit(node, OpBAndNot)
case token.XorAssign:
c.emit(node, OpBXor)
case token.ShlAssign:
c.emit(node, OpBShiftLeft)
case token.ShrAssign:
c.emit(node, OpBShiftRight)
}
// compile selector expressions (right to left)
for i := numSel - 1; i >= 0; i-- {
if err := c.Compile(selectors[i]); err != nil {
return err
}
}
switch symbol.Scope {
case ScopeGlobal:
if numSel > 0 {
c.emit(node, OpSetSelGlobal, symbol.Index, numSel)
} else {
c.emit(node, OpSetGlobal, symbol.Index)
}
case ScopeLocal:
if numSel > 0 {
c.emit(node, OpSetSelLocal, symbol.Index, numSel)
} else {
if op == token.Define && !symbol.LocalAssigned {
c.emit(node, OpDefineLocal, symbol.Index)
} else {
c.emit(node, OpSetLocal, symbol.Index)
}
}
// mark the symbol as local-assigned
symbol.LocalAssigned = true
case ScopeFree:
if numSel > 0 {
c.emit(node, OpSetSelFree, symbol.Index, numSel)
} else {
c.emit(node, OpSetFree, symbol.Index)
}
default:
panic(fmt.Errorf("invalid assignment variable scope: %s", symbol.Scope))
}
return nil
}
func resolveAssignLHS(expr ast.Expr) (name string, selectors []ast.Expr) {
switch term := expr.(type) {
case *ast.SelectorExpr:
name, selectors = resolveAssignLHS(term.Expr)
selectors = append(selectors, term.Sel)
return
case *ast.IndexExpr:
name, selectors = resolveAssignLHS(term.Expr)
selectors = append(selectors, term.Index)
case *ast.Ident:
name = term.Name
}
return
}
|
