neo-go/pkg/compiler/func_scope.go

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package compiler
import (
"go/ast"
"go/types"
)
// A funcScope represents the scope within the function context.
// It holds all the local variables along with the initialized struct positions.
type funcScope struct {
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// Identifier of the function.
name string
// Selector of the function if there is any. Only functions imported
// from other packages should have a selector.
selector ast.Expr
// The declaration of the function in the AST. Nil if this scope is not a function.
decl *ast.FuncDecl
// Package where the function is defined.
pkg *types.Package
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file *ast.File
// Program label of the scope
label uint16
// Range of opcodes corresponding to the function.
rng DebugRange
// Variables together with it's type in neo-vm.
variables []string
// deferStack is a stack containing encountered `defer` statements.
deferStack []deferInfo
// Local variables
vars varScope
// voidCalls are basically functions that return their value
// into nothing. The stack has their return value but there
// is nothing that consumes it. We need to keep track of
// these functions so we can cleanup (drop) the returned
// value from the stack. We also need to add every voidCall
// return value to the stack size.
voidCalls map[*ast.CallExpr]bool
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// Local variable counter.
i int
}
type deferInfo struct {
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catchLabel uint16
finallyLabel uint16
expr *ast.CallExpr
localIndex int
}
const (
finallyVarName = "<finally>"
exceptionVarName = "<exception>"
)
func (c *codegen) newFuncScope(decl *ast.FuncDecl, label uint16) *funcScope {
var name string
if decl.Name != nil {
name = decl.Name.Name
}
return &funcScope{
name: name,
decl: decl,
label: label,
pkg: c.currPkg.Types,
vars: newVarScope(),
voidCalls: map[*ast.CallExpr]bool{},
variables: []string{},
i: -1,
}
}
func (c *codegen) getFuncNameFromDecl(pkgPath string, decl *ast.FuncDecl) string {
name := decl.Name.Name
if decl.Recv != nil {
switch t := decl.Recv.List[0].Type.(type) {
case *ast.Ident:
name = t.Name + "." + name
case *ast.StarExpr:
name = t.X.(*ast.Ident).Name + "." + name
}
}
return c.getIdentName(pkgPath, name)
}
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// analyzeVoidCalls checks for functions that are not assigned
// and therefore we need to cleanup the return value from the stack.
func (c *funcScope) analyzeVoidCalls(node ast.Node) bool {
est, ok := node.(*ast.ExprStmt)
if ok {
ce, ok := est.X.(*ast.CallExpr)
if ok {
c.voidCalls[ce] = true
}
}
return true
}
func (c *funcScope) countArgs() int {
n := c.decl.Type.Params.NumFields()
if c.decl.Recv != nil {
n += c.decl.Recv.NumFields()
}
return n
}
// newVariable creates a new local variable or argument in the scope of the function.
func (c *funcScope) newVariable(t varType, name string) int {
return c.vars.newVariable(t, name)
}
// newLocal creates a new local variable into the scope of the function.
func (c *funcScope) newLocal(name string) int {
return c.newVariable(varLocal, name)
}