Preliminary support for 'copy' builtin function in exp/eval

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/2157042

diff --git a/src/pkg/exp/eval/expr.go b/src/pkg/exp/eval/expr.go
index 07e287caad6043f89d871b22311b1c40006879a4..9054ad8fbee88395d1e9554fd0e796af52c51662 100644 (file)
--- a/src/pkg/exp/eval/expr.go
+++ b/src/pkg/exp/eval/expr.go
@@ -1239,6 +1239,38 @@ func (a *exprInfo) compileBuiltinCallExpr(b *block, ft *FuncType, as []*expr) *e
                }
                return expr
 
+       case copyType:
+               if !checkCount(2, 2) {
+                       return nil
+               }
+               src := as[1]
+               dst := as[0]
+               if src.t != dst.t {
+                       a.diag("arguments to built-in function 'copy' must have same type\nsrc: %s\ndst: %s\n", src.t, dst.t)
+                       return nil
+               }
+               if _, ok := src.t.lit().(*SliceType); !ok {
+                       a.diag("src argument to 'copy' must be a slice (got: %s)", src.t)
+                       return nil
+               }
+               if _, ok := dst.t.lit().(*SliceType); !ok {
+                       a.diag("dst argument to 'copy' must be a slice (got: %s)", dst.t)
+                       return nil
+               }
+               expr := a.newExpr(IntType, "function call")
+               srcf := src.asSlice()
+               dstf := dst.asSlice()
+               expr.eval = func(t *Thread) int64 {
+                       src, dst := srcf(t), dstf(t)
+                       nelems := src.Len
+                       if nelems > dst.Len {
+                               nelems = dst.Len
+                       }
+                       dst.Base.Sub(0, nelems).Assign(t, src.Base.Sub(0, nelems))
+                       return nelems
+               }
+               return expr
+
        case lenType:
                if !checkCount(1, 1) {
                        return nil

diff --git a/src/pkg/exp/eval/type.go b/src/pkg/exp/eval/type.go
index 5ac1e46f9eff0ed837bb7b840caab9a4b78eabea..5a7ffb99c841c3e10c992edafe2d2025b7cf0aa6 100644 (file)
--- a/src/pkg/exp/eval/type.go
+++ b/src/pkg/exp/eval/type.go
@@ -712,6 +712,7 @@ var (
        panicType   = &FuncType{builtin: "panic"}
        printType   = &FuncType{builtin: "print"}
        printlnType = &FuncType{builtin: "println"}
+       copyType    = &FuncType{builtin: "copy"}
 )
 
 // Two function types are identical if they have the same number of
@@ -1249,6 +1250,7 @@ func init() {
        universe.DefineConst("cap", universePos, capType, nil)
        universe.DefineConst("close", universePos, closeType, nil)
        universe.DefineConst("closed", universePos, closedType, nil)
+       universe.DefineConst("copy", universePos, copyType, nil)
        universe.DefineConst("len", universePos, lenType, nil)
        universe.DefineConst("make", universePos, makeType, nil)
        universe.DefineConst("new", universePos, newType, nil)