ginger/expr/expr.go

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package expr
import (
"fmt"
"llvm.org/llvm/bindings/go/llvm"
)
// Expr represents the actual expression in question.
type Expr interface{}
// equaler is used to compare two expressions. The comparison should not take
// into account Token values, only the actual value being represented
type equaler interface {
equal(equaler) bool
}
// will panic if either Expr doesn't implement equaler
func exprEqual(e1, e2 Expr) bool {
eq1, ok1 := e1.(equaler)
eq2, ok2 := e2.(equaler)
if !ok1 || !ok2 {
panic(fmt.Sprintf("can't compare %T and %T", e1, e2))
}
return eq1.equal(eq2)
}
////////////////////////////////////////////////////////////////////////////////
// an Expr which simply wraps an existing llvm.Value
type llvmVal llvm.Value
/*
func voidVal(lctx LLVMCtx) llvmVal {
return llvmVal{lctx.B.CreateRetVoid()}
}
*/
////////////////////////////////////////////////////////////////////////////////
/*
// Void represents no data (size = 0)
type Void struct{}
func (v Void) equal(e equaler) bool {
_, ok := e.(Void)
return ok
}
*/
////////////////////////////////////////////////////////////////////////////////
/*
// Bool represents a true or false value
type Bool bool
func (b Bool) equal(e equaler) bool {
bb, ok := e.(Bool)
if !ok {
return false
}
return bb == b
}
*/
////////////////////////////////////////////////////////////////////////////////
// Int represents an integer value
type Int int64
func (i Int) equal(e equaler) bool {
ii, ok := e.(Int)
return ok && ii == i
}
////////////////////////////////////////////////////////////////////////////////
/*
// String represents a string value
type String string
func (s String) equal(e equaler) bool {
ss, ok := e.(String)
if !ok {
return false
}
return ss == s
}
*/
////////////////////////////////////////////////////////////////////////////////
// Identifier represents a binding to some other value which has been given a
// name
type Identifier string
func (id Identifier) equal(e equaler) bool {
idid, ok := e.(Identifier)
return ok && idid == id
}
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func isIdentifier(e Expr) bool {
_, ok := e.(Identifier)
return ok
}
////////////////////////////////////////////////////////////////////////////////
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// Macro is an identifier for a macro which can be used to transform
// expressions. The tokens for macros start with a '%', but the Macro identifier
// itself has that stripped off
type Macro string
// String returns the Macro with a '%' prepended to it
func (m Macro) String() string {
return "%" + string(m)
}
func (m Macro) equal(e equaler) bool {
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mm, ok := e.(Macro)
return ok && m == mm
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}
////////////////////////////////////////////////////////////////////////////////
// Tuple represents a fixed set of expressions which are interacted with as if
// they were a single value
type Tuple []Expr
// NewTuple returns a Tuple around the given list of Exprs
func NewTuple(ee ...Expr) Tuple {
return Tuple(ee)
}
func (tup Tuple) String() string {
return "(" + exprsJoin(tup) + ")"
}
func (tup Tuple) equal(e equaler) bool {
tuptup, ok := e.(Tuple)
return ok && exprsEqual(tup, tuptup)
}
////////////////////////////////////////////////////////////////////////////////
// Statement represents an actual action which will be taken. The input value is
// used as the input to the pipe, and the output of the pipe is the output of
// the statement
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type Statement struct {
Op, Arg Expr
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}
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// NewStatement returns a Statement whose Op is the first Expr. If the given
// list is empty Arg will be nil, if its length is one Arg will be that single
// Expr, otherwise Arg will be a Tuple of the list
func NewStatement(e Expr, ee ...Expr) Statement {
s := Statement{Op: e}
if len(ee) > 1 {
s.Arg = NewTuple(ee...)
} else if len(ee) == 1 {
s.Arg = ee[0]
}
return s
}
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func (s Statement) String() string {
return fmt.Sprintf("(%v %s)", s.Op, s.Arg)
}
func (s Statement) equal(e equaler) bool {
ss, ok := e.(Statement)
return ok && exprEqual(s.Op, ss.Op) && exprEqual(s.Arg, ss.Arg)
}
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////////////////////////////////////////////////////////////////////////////////
// Block represents a set of statements which share a scope, i.e. If one
// statement binds a variable the rest of the statements in the block can use
// that variable
type Block struct {
In []Expr
Stmts []Expr
Out []Expr
}
func (b Block) String() string {
return fmt.Sprintf(
"{[%s][%s][%s]}",
exprsJoin(b.In),
exprsJoin(b.Stmts),
exprsJoin(b.Out),
)
}
/*
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func (b Block) LLVMVal(ctx *Ctx, lctx LLVMCtx) llvm.Value {
name := randStr() // TODO make this based on token
// TODO make these based on actual statements
out := llvm.Int64Type()
in := []llvm.Type{}
fn := llvm.AddFunction(lctx.M, name, llvm.FunctionType(out, in, false))
block := llvm.AddBasicBlock(fn, "entry")
lctx.B.SetInsertPoint(block, block.FirstInstruction())
var v llvm.Value
for _, se := range b {
v = se.Actual.LLVMVal(ctx, lctx)
}
// last v is used as return
// TODO empty return
lctx.B.CreateRet(v)
return fn
}
*/
func (b Block) equal(e equaler) bool {
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bb, ok := e.(Block)
return ok &&
exprsEqual(b.In, bb.In) &&
exprsEqual(b.Stmts, bb.Stmts) &&
exprsEqual(b.Out, bb.Out)
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}