Refactoring

This puts through a number of minor refactorings which are now possible,
and removes some code which is no longer used.

pkg/air/eval.go

@@ -9,7 +9,7 @@ import (
 // value at that row of the column in question or nil is that row is
 // out-of-bounds.
 func (e *ColumnAccess) EvalAt(k int, tr trace.Trace) *fr.Element {
-	val := tr.ColumnByIndex(e.Column).Get(k + e.Shift)
+	val := tr.Column(e.Column).Get(k + e.Shift)
 
 	var clone fr.Element
 	// Clone original value

pkg/cmd/trace.go

@@ -60,7 +60,7 @@ func filterColumns(tr trace.Trace, prefix string) trace.Trace {
 	ntr := trace.EmptyArrayTrace()
 	//
 	for i := uint(0); i < tr.Width(); i++ {
-		ith := tr.ColumnByIndex(i)
+		ith := tr.Column(i)
 		if strings.HasPrefix(ith.Name(), prefix) {
 			ntr.Add(ith)
 		}
@@ -73,7 +73,7 @@ func listColumns(tr trace.Trace) {
 	tbl := util.NewTablePrinter(3, tr.Width())
 
 	for i := uint(0); i < tr.Width(); i++ {
-		ith := tr.ColumnByIndex(i)
+		ith := tr.Column(i)
 		elems := fmt.Sprintf("%d rows", ith.Height())
 		bytes := fmt.Sprintf("%d bytes", ith.Width()*ith.Height())
 		tbl.SetRow(i, ith.Name(), elems, bytes)
@@ -93,7 +93,7 @@ func printTrace(start uint, end uint, max_width uint, tr trace.Trace) {
 	}
 
 	for i := uint(0); i < tr.Width(); i++ {
-		ith := tr.ColumnByIndex(i)
+		ith := tr.Column(i)
 		tbl.Set(0, i+1, ith.Name())
 
 		if start < ith.Height() {

pkg/cmd/util.go

@@ -102,7 +102,7 @@ func readTraceFile(filename string) trace.Trace {
 		//
 		switch ext {
 		case ".json":
-			tr, err = trace.ParseJsonTrace(bytes)
+			tr, err = json.FromBytes(bytes)
 			if err == nil {
 				return tr
 			}

pkg/hir/eval.go

@@ -9,7 +9,7 @@ import (
 // value at that row of the column in question or nil is that row is
 // out-of-bounds.
 func (e *ColumnAccess) EvalAllAt(k int, tr trace.Trace) []*fr.Element {
-	val := tr.ColumnByIndex(e.Column).Get(k + e.Shift)
+	val := tr.Column(e.Column).Get(k + e.Shift)
 
 	var clone fr.Element
 	// Clone original value

pkg/mir/eval.go

@@ -9,7 +9,7 @@ import (
 // value at that row of the column in question or nil is that row is
 // out-of-bounds.
 func (e *ColumnAccess) EvalAt(k int, tr trace.Trace) *fr.Element {
-	val := tr.ColumnByIndex(e.Column).Get(k + e.Shift)
+	val := tr.Column(e.Column).Get(k + e.Shift)
 
 	var clone fr.Element
 	// Clone original value

pkg/schema/alignment.go

@@ -47,7 +47,7 @@ func alignWith(expand bool, p tr.Trace, schema Schema) error {
 					return fmt.Errorf("trace missing column %s", schemaName)
 				}
 
-				traceName := p.ColumnByIndex(index).Name()
+				traceName := p.Column(index).Name()
 				// Check alignment
 				if traceName != schemaName {
 					// Not aligned --- so fix
@@ -74,7 +74,7 @@ func alignWith(expand bool, p tr.Trace, schema Schema) error {
 	unknowns := make([]string, n)
 	// Determine names of unknown columns.
 	for i := index; i < ncols; i++ {
-		unknowns[i-index] = p.ColumnByIndex(i).Name()
+		unknowns[i-index] = p.Column(i).Name()
 	}
 	//
 	return fmt.Errorf("trace contains unknown columns: %v", unknowns)

pkg/schema/assignment/byte_decomposition.go

@@ -5,7 +5,7 @@ import (
 
 	"github.com/consensys/gnark-crypto/ecc/bls12-377/fr"
 	"github.com/consensys/go-corset/pkg/schema"
-	tr "github.com/consensys/go-corset/pkg/trace"
+	"github.com/consensys/go-corset/pkg/trace"
 	"github.com/consensys/go-corset/pkg/util"
 )
 
@@ -62,13 +62,13 @@ func (p *ByteDecomposition) IsComputed() bool {
 // ExpandTrace expands a given trace to include the columns specified by a given
 // ByteDecomposition.  This requires computing the value of each byte column in
 // the decomposition.
-func (p *ByteDecomposition) ExpandTrace(tr tr.Trace) error {
+func (p *ByteDecomposition) ExpandTrace(tr trace.Trace) error {
 	// Calculate how many bytes required.
 	n := len(p.targets)
 	// Identify target column
-	target := tr.ColumnByIndex(p.source)
+	target := tr.Column(p.source)
 	// Extract column data to decompose
-	data := tr.ColumnByIndex(p.source).Data()
+	data := tr.Column(p.source).Data()
 	// Construct byte column data
 	cols := make([][]*fr.Element, n)
 	// Initialise columns
@@ -86,7 +86,7 @@ func (p *ByteDecomposition) ExpandTrace(tr tr.Trace) error {
 	padding := decomposeIntoBytes(target.Padding(), n)
 	// Finally, add byte columns to trace
 	for i := 0; i < n; i++ {
-		tr.AddColumn(p.targets[i].Name(), cols[i], padding[i])
+		tr.Add(trace.NewFieldColumn(p.targets[i].Name(), cols[i], padding[i]))
 	}
 	// Done
 	return nil

pkg/schema/assignment/computed.go

@@ -6,7 +6,7 @@ import (
 	"github.com/consensys/gnark-crypto/ecc/bls12-377/fr"
 	"github.com/consensys/go-corset/pkg/schema"
 	sc "github.com/consensys/go-corset/pkg/schema"
-	tr "github.com/consensys/go-corset/pkg/trace"
+	"github.com/consensys/go-corset/pkg/trace"
 	"github.com/consensys/go-corset/pkg/util"
 )
 
@@ -75,7 +75,7 @@ func (p *ComputedColumn[E]) RequiredSpillage() uint {
 // ExpandTrace attempts to a new column to the trace which contains the result
 // of evaluating a given expression on each row.  If the column already exists,
 // then an error is flagged.
-func (p *ComputedColumn[E]) ExpandTrace(tr tr.Trace) error {
+func (p *ComputedColumn[E]) ExpandTrace(tr trace.Trace) error {
 	if tr.HasColumn(p.name) {
 		return fmt.Errorf("Computed column already exists ({%s})", p.name)
 	}
@@ -96,7 +96,7 @@ func (p *ComputedColumn[E]) ExpandTrace(tr tr.Trace) error {
 	// the padding value for *this* column.
 	padding := p.expr.EvalAt(-1, tr)
 	// Colunm needs to be expanded.
-	tr.AddColumn(p.name, data, padding)
+	tr.Add(trace.NewFieldColumn(p.name, data, padding))
 	// Done
 	return nil
 }

pkg/schema/assignment/lexicographic_sort.go

@@ -85,8 +85,8 @@ func (p *LexicographicSort) ExpandTrace(tr trace.Trace) error {
 		delta[i] = &zero
 		// Decide which row is the winner (if any)
 		for j := 0; j < ncols; j++ {
-			prev := tr.ColumnByIndex(p.sources[j]).Get(i - 1)
-			curr := tr.ColumnByIndex(p.sources[j]).Get(i)
+			prev := tr.Column(p.sources[j]).Get(i - 1)
+			curr := tr.Column(p.sources[j]).Get(i)
 
 			if !set && prev != nil && prev.Cmp(curr) != 0 {
 				var diff fr.Element
@@ -108,11 +108,11 @@ func (p *LexicographicSort) ExpandTrace(tr trace.Trace) error {
 		}
 	}
 	// Add delta column data
-	tr.AddColumn(p.targets[0].Name(), delta, &zero)
+	tr.Add(trace.NewFieldColumn(p.targets[0].Name(), delta, &zero))
 	// Add bit column data
 	for i := 0; i < ncols; i++ {
 		bitName := p.targets[1+i].Name()
-		tr.AddColumn(bitName, bit[i], &zero)
+		tr.Add(trace.NewFieldColumn(bitName, bit[i], &zero))
 	}
 	// Done.
 	return nil

pkg/schema/assignment/sorted_permutation.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/consensys/gnark-crypto/ecc/bls12-377/fr"
 	"github.com/consensys/go-corset/pkg/schema"
+	"github.com/consensys/go-corset/pkg/trace"
 	tr "github.com/consensys/go-corset/pkg/trace"
 	"github.com/consensys/go-corset/pkg/util"
 )
@@ -119,7 +120,7 @@ func (p *SortedPermutation) ExpandTrace(tr tr.Trace) error {
 	for i := 0; i < len(p.sources); i++ {
 		src := p.sources[i]
 		// Read column data to initialise permutation.
-		data := tr.ColumnByIndex(src).Data()
+		data := tr.Column(src).Data()
 		// Copy column data to initialise permutation.
 		cols[i] = make([]*fr.Element, len(data))
 		copy(cols[i], data)
@@ -131,8 +132,8 @@ func (p *SortedPermutation) ExpandTrace(tr tr.Trace) error {
 
 	for i := p.Columns(); i.HasNext(); {
 		dstColName := i.Next().Name()
-		srcCol := tr.ColumnByIndex(p.sources[index])
-		tr.AddColumn(dstColName, cols[index], srcCol.Padding())
+		srcCol := tr.Column(p.sources[index])
+		tr.Add(trace.NewFieldColumn(dstColName, cols[index], srcCol.Padding()))
 
 		index++
 	}

pkg/schema/constraint/permutation.go

@@ -77,7 +77,7 @@ func sliceColumns(columns []uint, tr trace.Trace) [][]*fr.Element {
 	cols := make([][]*fr.Element, len(columns))
 	// Slice out the data
 	for i, n := range columns {
-		nth := tr.ColumnByIndex(n)
+		nth := tr.Column(n)
 		cols[i] = nth.Data()
 	}
 	// Done

pkg/schema/constraint/range.go

@@ -37,7 +37,7 @@ func NewRangeConstraint(column uint, bound *fr.Element) *RangeConstraint {
 // Accepts checks whether a range constraint evaluates to zero on
 // every row of a table. If so, return nil otherwise return an error.
 func (p *RangeConstraint) Accepts(tr trace.Trace) error {
-	column := tr.ColumnByIndex(p.column)
+	column := tr.Column(p.column)
 	for k := 0; k < int(tr.Height()); k++ {
 		// Get the value on the kth row
 		kth := column.Get(k)

pkg/schema/constraint/type.go

@@ -39,7 +39,7 @@ func (p *TypeConstraint) Type() schema.Type {
 // Accepts checks whether a range constraint evaluates to zero on
 // every row of a table. If so, return nil otherwise return an error.
 func (p *TypeConstraint) Accepts(tr trace.Trace) error {
-	column := tr.ColumnByIndex(p.column)
+	column := tr.Column(p.column)
 	for k := 0; k < int(tr.Height()); k++ {
 		// Get the value on the kth row
 		kth := column.Get(k)

pkg/schema/schemas.go

@@ -1,8 +1,6 @@
 package schema
 
 import (
-	"fmt"
-
 	tr "github.com/consensys/go-corset/pkg/trace"
 )
 
@@ -69,26 +67,3 @@ func ColumnIndexOf(schema Schema, name string) (uint, bool) {
 		return c.Name() == name
 	})
 }
-
-// ColumnByName returns the column with the matching name, or panics if no such
-// column exists.
-func ColumnByName(schema Schema, name string) Column {
-	var col Column
-	// Attempt to determine the index of this column
-	_, ok := schema.Columns().Find(func(c Column) bool {
-		col = c
-		return c.Name() == name
-	})
-	// If we found it, then done.
-	if ok {
-		return col
-	}
-	// Otherwise panic.
-	panic(fmt.Sprintf("unknown column %s", name))
-}
-
-// HasColumn checks whether a column of the given name is declared within the schema.
-func HasColumn(schema Schema, name string) bool {
-	_, ok := ColumnIndexOf(schema, name)
-	return ok
-}

pkg/test/ir_test.go

@@ -12,6 +12,7 @@ import (
 	"github.com/consensys/go-corset/pkg/schema"
 	sc "github.com/consensys/go-corset/pkg/schema"
 	"github.com/consensys/go-corset/pkg/trace"
+	"github.com/consensys/go-corset/pkg/trace/json"
 )
 
 // Determines the (relative) location of the test directory.  That is
@@ -469,7 +470,7 @@ func ReadTracesFile(name string, ext string) []*trace.ArrayTrace {
 	for i, line := range lines {
 		// Parse input line as JSON
 		if line != "" && !strings.HasPrefix(line, ";;") {
-			tr, err := trace.ParseJsonTrace([]byte(line))
+			tr, err := json.FromBytes([]byte(line))
 			if err != nil {
 				msg := fmt.Sprintf("%s.%s:%d: %s", name, ext, i+1, err)
 				panic(msg)

pkg/trace/array_trace.go

@@ -67,24 +67,11 @@ func (p *ArrayTrace) Columns() []Column {
 	return p.columns
 }
 
-// ColumnByIndex looks up a column based on its index.
-func (p *ArrayTrace) ColumnByIndex(index uint) Column {
+// Column looks up a column based on its index.
+func (p *ArrayTrace) Column(index uint) Column {
 	return p.columns[index]
 }
 
-// ColumnByName looks up a column based on its name.  If the column doesn't
-// exist, then nil is returned.
-func (p *ArrayTrace) ColumnByName(name string) Column {
-	for _, c := range p.columns {
-		if name == c.Name() {
-			// Matched column
-			return c
-		}
-	}
-
-	return nil
-}
-
 // HasColumn checks whether the trace has a given named column (or not).
 func (p *ArrayTrace) HasColumn(name string) bool {
 	_, ok := p.ColumnIndex(name)
@@ -120,18 +107,7 @@ func (p *ArrayTrace) Add(column Column) {
 
 // AddColumn adds a new column of data to this trace.
 func (p *ArrayTrace) AddColumn(name string, data []*fr.Element, padding *fr.Element) {
-	// Sanity check the column does not already exist.
-	if p.HasColumn(name) {
-		panic("column already exists")
-	}
-	// Construct new column
-	column := FieldColumn{name, data, padding}
-	// Append it
-	p.columns = append(p.columns, &column)
-	// Update maximum height
-	if uint(len(data)) > p.height {
-		p.height = uint(len(data))
-	}
+	p.Add(&FieldColumn{name, data, padding})
 }
 
 // Height determines the maximum height of any column within this trace.

pkg/trace/field_column.go

@@ -21,6 +21,11 @@ type FieldColumn struct {
 	padding *fr.Element
 }
 
+// NewFieldColumn constructs a FieldColumn with the give name, data and padding.
+func NewFieldColumn(name string, data []*fr.Element, padding *fr.Element) *FieldColumn {
+	return &FieldColumn{name, data, padding}
+}
+
 // Name returns the name of the given column.
 func (p *FieldColumn) Name() string {
 	return p.name

pkg/trace/json/reader.go

@@ -0,0 +1,35 @@
+package json
+
+import (
+	"encoding/json"
+	"math/big"
+
+	"github.com/consensys/gnark-crypto/ecc/bls12-377/fr"
+	"github.com/consensys/go-corset/pkg/trace"
+	"github.com/consensys/go-corset/pkg/util"
+)
+
+// FromBytes parses a trace expressed in JSON notation.  For example, {"X":
+// [0], "Y": [1]} is a trace containing one row of data each for two columns "X"
+// and "Y".
+func FromBytes(bytes []byte) (*trace.ArrayTrace, error) {
+	var zero fr.Element = fr.NewElement((0))
+
+	var rawData map[string][]*big.Int
+	// Unmarshall
+	jsonErr := json.Unmarshal(bytes, &rawData)
+	if jsonErr != nil {
+		return nil, jsonErr
+	}
+
+	trace := trace.EmptyArrayTrace()
+
+	for name, rawInts := range rawData {
+		// Translate raw bigints into raw field elements
+		rawElements := util.ToFieldElements(rawInts)
+		// Add new column to the trace
+		trace.AddColumn(name, rawElements, &zero)
+	}
+	// Done.
+	return trace, nil
+}

pkg/trace/json/writer.go

@@ -17,7 +17,7 @@ func ToJsonString(tr trace.Trace) string {
 			builder.WriteString(", ")
 		}
 
-		ith := tr.ColumnByIndex(i)
+		ith := tr.Column(i)
 
 		builder.WriteString("\"")
 		builder.WriteString(ith.Name())

pkg/trace/lt/writer.go

@@ -38,7 +38,7 @@ func WriteBytes(tr trace.Trace, buf io.Writer) error {
 	}
 	// Write header information
 	for i := uint(0); i < ncols; i++ {
-		col := tr.ColumnByIndex(i)
+		col := tr.Column(i)
 		// Write name length
 		nameBytes := []byte(col.Name())
 		nameLen := uint16(len(nameBytes))
@@ -62,7 +62,7 @@ func WriteBytes(tr trace.Trace, buf io.Writer) error {
 	}
 	// Write column data information
 	for i := uint(0); i < ncols; i++ {
-		col := tr.ColumnByIndex(i)
+		col := tr.Column(i)
 		if err := col.Write(buf); err != nil {
 			return err
 		}