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Improve semantics of tokens and values obtained from them.

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Now gg.Values can carry the token used to parse them, which will be
useful later when generating errors.
This commit is contained in:
Brian Picciano 2021-12-28 09:49:02 -07:00
parent 33e59a3836
commit c5aa582226
6 changed files with 132 additions and 94 deletions
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28
gg/decoder.go
View File

@ -19,7 +19,7 @@ const (
)
func decoderErr(tok LexerToken, err error) error {
return fmt.Errorf("%d:%d: %w", tok.Row, tok.Col, err)
return fmt.Errorf("%s: %w", tok.errPrefix(), err)
}
func decoderErrf(tok LexerToken, str string, args ...interface{}) error {
@ -53,7 +53,7 @@ func (d *decoder) parseSingleValue(
tok, rest := toks[0], toks[1:]
if len(rest) == 0 {
return Value{}, nil, false, decoderErrf(tok, "cannot be final token, possibly missing %q", punctTerm)
return ZeroValue, nil, false, decoderErrf(tok, "cannot be final token, possibly missing %q", punctTerm)
}
termed := isTerm(rest[0])
@ -65,20 +65,20 @@ func (d *decoder) parseSingleValue(
switch tok.Kind {
case LexerTokenKindName:
return Value{Name: &tok.Value}, rest, termed, nil
return Value{Name: &tok.Value, LexerToken: &tok}, rest, termed, nil
case LexerTokenKindNumber:
i, err := strconv.ParseInt(tok.Value, 10, 64)
if err != nil {
return Value{}, nil, false, decoderErrf(tok, "parsing %q as integer: %w", tok.Value, err)
return ZeroValue, nil, false, decoderErrf(tok, "parsing %q as integer: %w", tok.Value, err)
}
return Value{Number: &i}, rest, termed, nil
return Value{Number: &i, LexerToken: &tok}, rest, termed, nil
case LexerTokenKindPunctuation:
return Value{}, nil, false, decoderErrf(tok, "expected value, found punctuation %q", tok.Value)
return ZeroValue, nil, false, decoderErrf(tok, "expected value, found punctuation %q", tok.Value)
default:
panic(fmt.Sprintf("unexpected token kind %q", tok.Kind))
@ -116,7 +116,7 @@ func (d *decoder) parseOpenEdge(
}
if termed {
return ValueOut(val, Value{}), toks, nil
return ValueOut(val, ZeroValue), toks, nil
}
opTok, toks := toks[0], toks[1:]
@ -181,7 +181,7 @@ func (d *decoder) parseTuple(
toks = toks[1:]
}
return TupleOut(edges, Value{}), toks, nil
return TupleOut(edges, ZeroValue), toks, nil
}
// returned boolean value indicates if the token following the graph is a term.
@ -211,18 +211,18 @@ func (d *decoder) parseGraphValue(
break
}
return Value{}, nil, false, decoderErrf(openTok, "no matching %q", punctCloseGraph)
return ZeroValue, nil, false, decoderErrf(openTok, "no matching %q", punctCloseGraph)
} else if closingTok := toks[0]; isPunct(closingTok, punctCloseGraph) {
if !expectWrappers {
return Value{}, nil, false, decoderErrf(closingTok, "unexpected %q", punctCloseGraph)
return ZeroValue, nil, false, decoderErrf(closingTok, "unexpected %q", punctCloseGraph)
}
toks = toks[1:]
if len(toks) == 0 {
return Value{}, nil, false, decoderErrf(closingTok, "cannot be final token, possibly missing %q", punctTerm)
return ZeroValue, nil, false, decoderErrf(closingTok, "cannot be final token, possibly missing %q", punctTerm)
}
break
@ -231,7 +231,7 @@ func (d *decoder) parseGraphValue(
var err error
if g, toks, err = d.parseValIn(g, toks); err != nil {
return Value{}, nil, false, err
return ZeroValue, nil, false, err
}
}
@ -241,6 +241,8 @@ func (d *decoder) parseGraphValue(
return val, toks, true, nil
}
val.LexerToken = &openTok
termed := isTerm(toks[0])
if termed {
@ -276,7 +278,7 @@ func (d *decoder) parseValIn(into *Graph, toks []LexerToken) (*Graph, []LexerTok
return nil, nil, err
}
dstVal := Value{Name: &dst.Value}
dstVal := Value{Name: &dst.Value, LexerToken: &dst}
return into.AddValueIn(oe, dstVal), toks, nil
}

18
gg/decoder_test.go
View File

@ -27,7 +27,7 @@ func TestDecoder(t *testing.T) {
},
{
in: "out = 1;",
exp: ZeroGraph.AddValueIn(ValueOut(i(1), Value{}), n("out")),
exp: ZeroGraph.AddValueIn(ValueOut(i(1), ZeroValue), n("out")),
},
{
in: "out = incr < 1;",
@ -49,7 +49,7 @@ func TestDecoder(t *testing.T) {
TupleOut(
[]OpenEdge{TupleOut(
[]OpenEdge{
ValueOut(i(1), Value{}),
ValueOut(i(1), ZeroValue),
ValueOut(i(2), n("c")),
TupleOut(
[]OpenEdge{ValueOut(i(3), n("e"))},
@ -69,11 +69,11 @@ func TestDecoder(t *testing.T) {
TupleOut(
[]OpenEdge{TupleOut(
[]OpenEdge{
ValueOut(i(1), Value{}),
ValueOut(i(1), ZeroValue),
TupleOut(
[]OpenEdge{
ValueOut(i(2), n("d")),
ValueOut(i(3), Value{}),
ValueOut(i(3), ZeroValue),
},
n("c"),
),
@ -90,7 +90,7 @@ func TestDecoder(t *testing.T) {
exp: ZeroGraph.AddValueIn(
ValueOut(
Value{Graph: ZeroGraph.
AddValueIn(ValueOut(i(1), Value{}), n("a")).
AddValueIn(ValueOut(i(1), ZeroValue), n("a")).
AddValueIn(
TupleOut(
[]OpenEdge{
@ -101,7 +101,7 @@ func TestDecoder(t *testing.T) {
n("b"),
),
},
Value{},
ZeroValue,
),
n("out"),
),
@ -114,7 +114,7 @@ func TestDecoder(t *testing.T) {
ValueOut(
i(2),
Value{Graph: ZeroGraph.
AddValueIn(ValueOut(i(1), Value{}), n("b")),
AddValueIn(ValueOut(i(1), ZeroValue), n("b")),
},
),
},
@ -126,8 +126,8 @@ func TestDecoder(t *testing.T) {
{
in: "a = 1; b = 2;",
exp: ZeroGraph.
AddValueIn(ValueOut(i(1), Value{}), n("a")).
AddValueIn(ValueOut(i(2), Value{}), n("b")),
AddValueIn(ValueOut(i(1), ZeroValue), n("a")).
AddValueIn(ValueOut(i(2), ZeroValue), n("b")),
},
}

33
gg/gg.go
View File

@ -6,22 +6,37 @@ import (
"strings"
)
// Value represents a value being stored in a Graph. No more than one field may
// be non-nil. No fields being set indicates lack of value.
// ZeroValue is a Value with no fields set.
var ZeroValue Value
// Value represents a value being stored in a Graph.
type Value struct {
// Only one of these fields may be set
Name *string
Number *int64
Graph *Graph
// TODO coming soon!
// String *string
// Optional fields indicating the token which was used to construct this
// Value, if any.
LexerToken *LexerToken
}
// IsZero returns true if the Value is the zero value (none of the sub-value
// fields are set). LexerToken is ignored for this check.
func (v Value) IsZero() bool {
v.LexerToken = nil
return v == Value{}
}
// Equal returns true if the passed in Value is equivalent.
func (v Value) Equal(v2 Value) bool {
switch {
case v == Value{} && v2 == Value{}:
case v.IsZero() && v2.IsZero():
return true
case v.Name != nil && v2.Name != nil && *v.Name == *v2.Name:
@ -42,8 +57,8 @@ func (v Value) String() string {
switch {
case v == Value{}:
return "<noval>"
case v.IsZero():
return "<zero>"
case v.Name != nil:
return *v.Name
@ -105,24 +120,24 @@ func ValueOut(val, edgeVal Value) OpenEdge {
// represents an edge (with edgeVal attached to it) coming from the
// TupleVertex comprised of the given ordered-set of input edges.
//
// If len(ins) == 1 and edgeVal == Value{}, then that single OpenEdge is
// If len(ins) == 1 && edgeVal.IsZero(), then that single OpenEdge is
// returned as-is.
func TupleOut(ins []OpenEdge, edgeVal Value) OpenEdge {
if len(ins) == 1 {
if edgeVal == (Value{}) {
if edgeVal.IsZero() {
return ins[0]
}
if ins[0].val == (Value{}) {
if ins[0].val.IsZero() {
return ins[0].WithEdgeVal(edgeVal)
}
}
return OpenEdge{
fromV: mkVertex(TupleVertex, Value{}, ins...),
fromV: mkVertex(TupleVertex, ZeroValue, ins...),
val: edgeVal,
}
}

4
gg/gg_test.go
View File

@ -61,7 +61,7 @@ func TestEqual(t *testing.T) {
// equivalent to just that edge.
a: ZeroGraph.AddValueIn(TupleOut([]OpenEdge{
ValueOut(i(1), n("ident")),
}, Value{}), n("out")),
}, ZeroValue), n("out")),
b: ZeroGraph.AddValueIn(ValueOut(i(1), n("ident")), n("out")),
exp: true,
},
@ -70,7 +70,7 @@ func TestEqual(t *testing.T) {
// edgeVal should be equivalent to just that edge with the tuple's
// edge value.
a: ZeroGraph.AddValueIn(TupleOut([]OpenEdge{
ValueOut(i(1), Value{}),
ValueOut(i(1), ZeroValue),
}, n("ident")), n("out")),
b: ZeroGraph.AddValueIn(ValueOut(i(1), n("ident")), n("out")),
exp: true,

43
gg/lexer.go
View File

@ -8,15 +8,26 @@ import (
"unicode"
)
// LexerError is returned by Lexer when an unexpected error occurs parsing a
// stream of LexerTokens.
type LexerError struct {
Err error
// LexerLocation describes the location in a file where a particular token was
// parsed from.
type LexerLocation struct {
Row, Col int
}
func (l LexerLocation) String() string {
return fmt.Sprintf("%d:%d", l.Row, l.Col)
}
// LexerError is returned by Lexer when an unexpected error occurs parsing a
// stream of LexerTokens.
type LexerError struct {
Err error
Location LexerLocation
}
func (e *LexerError) Error() string {
return fmt.Sprintf("%d:%d: %s", e.Row, e.Col, e.Err.Error())
return fmt.Sprintf("%s: %s", e.Location.String(), e.Err.Error())
}
func (e *LexerError) Unwrap() error {
@ -39,7 +50,11 @@ type LexerToken struct {
Kind LexerTokenKind
Value string // never empty string
Row, Col int
Location LexerLocation
}
func (t LexerToken) errPrefix() string {
return fmt.Sprintf("%s: at %q", t.Location.String(), t.Value)
}
// Lexer is used to parse a string stream into a sequence of tokens which can
@ -90,8 +105,10 @@ func (l *lexer) fmtErr(err error) *LexerError {
return &LexerError{
Err: err,
Row: row,
Col: col,
Location: LexerLocation{
Row: row,
Col: col,
},
}
}
@ -167,7 +184,9 @@ func (l *lexer) readWhile(
return LexerToken{
Kind: kind,
Value: l.stringBuilder.String(),
Row: row, Col: col,
Location: LexerLocation{
Row: row, Col: col,
},
}, lexErr
}
@ -236,8 +255,10 @@ func (l *lexer) next() (LexerToken, *LexerError) {
return LexerToken{
Kind: LexerTokenKindPunctuation,
Value: string(r),
Row: l.lastRow,
Col: l.lastCol,
Location: LexerLocation{
Row: l.lastRow,
Col: l.lastCol,
},
}, nil
case unicode.IsSpace(r):

100
gg/lexer_test.go
View File

@ -23,9 +23,9 @@ func TestLexer(t *testing.T) {
in: "foo",
exp: []LexerToken{
{
Kind: LexerTokenKindName,
Value: "foo",
Row: 0, Col: 0,
Kind: LexerTokenKindName,
Value: "foo",
Location: LexerLocation{Row: 0, Col: 0},
},
},
},
@ -33,29 +33,29 @@ func TestLexer(t *testing.T) {
in: "foo bar\nf-o f0O Foo",
exp: []LexerToken{
{
Kind: LexerTokenKindName,
Value: "foo",
Row: 0, Col: 0,
Kind: LexerTokenKindName,
Value: "foo",
Location: LexerLocation{Row: 0, Col: 0},
},
{
Kind: LexerTokenKindName,
Value: "bar",
Row: 0, Col: 4,
Kind: LexerTokenKindName,
Value: "bar",
Location: LexerLocation{Row: 0, Col: 4},
},
{
Kind: LexerTokenKindName,
Value: "f-o",
Row: 1, Col: 0,
Kind: LexerTokenKindName,
Value: "f-o",
Location: LexerLocation{Row: 1, Col: 0},
},
{
Kind: LexerTokenKindName,
Value: "f0O",
Row: 1, Col: 4,
Kind: LexerTokenKindName,
Value: "f0O",
Location: LexerLocation{Row: 1, Col: 4},
},
{
Kind: LexerTokenKindName,
Value: "Foo",
Row: 1, Col: 8,
Kind: LexerTokenKindName,
Value: "Foo",
Location: LexerLocation{Row: 1, Col: 8},
},
},
},
@ -63,19 +63,19 @@ func TestLexer(t *testing.T) {
in: "1 100 -100",
exp: []LexerToken{
{
Kind: LexerTokenKindNumber,
Value: "1",
Row: 0, Col: 0,
Kind: LexerTokenKindNumber,
Value: "1",
Location: LexerLocation{Row: 0, Col: 0},
},
{
Kind: LexerTokenKindNumber,
Value: "100",
Row: 0, Col: 2,
Kind: LexerTokenKindNumber,
Value: "100",
Location: LexerLocation{Row: 0, Col: 2},
},
{
Kind: LexerTokenKindNumber,
Value: "-100",
Row: 0, Col: 6,
Kind: LexerTokenKindNumber,
Value: "-100",
Location: LexerLocation{Row: 0, Col: 6},
},
},
},
@ -83,39 +83,39 @@ func TestLexer(t *testing.T) {
in: "1<2!-3 ()",
exp: []LexerToken{
{
Kind: LexerTokenKindNumber,
Value: "1",
Row: 0, Col: 0,
Kind: LexerTokenKindNumber,
Value: "1",
Location: LexerLocation{Row: 0, Col: 0},
},
{
Kind: LexerTokenKindPunctuation,
Value: "<",
Row: 0, Col: 1,
Kind: LexerTokenKindPunctuation,
Value: "<",
Location: LexerLocation{Row: 0, Col: 1},
},
{
Kind: LexerTokenKindNumber,
Value: "2",
Row: 0, Col: 2,
Kind: LexerTokenKindNumber,
Value: "2",
Location: LexerLocation{Row: 0, Col: 2},
},
{
Kind: LexerTokenKindPunctuation,
Value: "!",
Row: 0, Col: 3,
Kind: LexerTokenKindPunctuation,
Value: "!",
Location: LexerLocation{Row: 0, Col: 3},
},
{
Kind: LexerTokenKindNumber,
Value: "-3",
Row: 0, Col: 4,
Kind: LexerTokenKindNumber,
Value: "-3",
Location: LexerLocation{Row: 0, Col: 4},
},
{
Kind: LexerTokenKindPunctuation,
Value: "(",
Row: 0, Col: 7,
Kind: LexerTokenKindPunctuation,
Value: "(",
Location: LexerLocation{Row: 0, Col: 7},
},
{
Kind: LexerTokenKindPunctuation,
Value: ")",
Row: 0, Col: 8,
Kind: LexerTokenKindPunctuation,
Value: ")",
Location: LexerLocation{Row: 0, Col: 8},
},
},
},
@ -142,8 +142,8 @@ func TestLexer(t *testing.T) {
inParts := strings.Split(test.in, "\n")
assert.ErrorIs(t, lexErr, expErr)
assert.Equal(t, lexErr.Row, len(inParts)-1)
assert.Equal(t, lexErr.Col, len(inParts[len(inParts)-1]))
assert.Equal(t, lexErr.Location.Row, len(inParts)-1)
assert.Equal(t, lexErr.Location.Col, len(inParts[len(inParts)-1]))
})
}