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path expression improvements
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- introduce sequence type to prevent array mishandling
- wrap output from generic sequence to prevent array collapse
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@shortercode
shortercode committed Nov 15, 2022
1 parent 946f724 commit 49e3548
Showing 1 changed file with 39 additions and 25 deletions.
64 changes: 39 additions & 25 deletions src/runtime/expressions/path.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,15 @@ import { Range } from '../../Range';
import type { SimpleArray, SimpleObject, SimpleValue } from '../../SimpleValue.type';
import { eval_any_expr, ExpressionEnvironment, extended_typeof } from '../expression';

export type Sequence = SimpleArray;
export type Sequence = SimpleArray & { sequence: true };

function create_sequence (...data: SimpleArray): Sequence {
return data as Sequence;
}

function concat_sequence (seq: SimpleArray, add: SimpleArray): Sequence {
return seq.concat(add) as Sequence;
}

export function eval_path_expr(ctx: ExpressionEnvironment, expr: PathExpression, value: SimpleValue): SimpleValue {
const head_value = expr.head ? eval_any_expr(ctx, expr.head, value) : value;
Expand All @@ -12,7 +20,7 @@ export function eval_path_expr(ctx: ExpressionEnvironment, expr: PathExpression,
return undefined;
}

return eval_path_sequence(ctx, expr.segments, [head_value]);
return eval_path_sequence(ctx, expr.segments, create_sequence(head_value));
}

export function eval_path_sequence(ctx: ExpressionEnvironment, segments: PathSegment[], sequence: Sequence): SimpleValue {
Expand Down Expand Up @@ -51,7 +59,7 @@ export function eval_path_segment(ctx: ExpressionEnvironment, op: PathSegment, s
}

export function eval_filter_op(ctx: ExpressionEnvironment, expr: FilterSegment, sequence: Sequence): Sequence {
const result: SimpleValue[] = [];
const result = create_sequence();

const match = (val: SimpleValue, i: number, l: number): boolean => {
const predicate = eval_any_expr(ctx, expr.expression, val);
Expand Down Expand Up @@ -115,22 +123,22 @@ export function eval_reduce_op(ctx: ExpressionEnvironment, expr: ReduceSegment,
}
}

return [result];
return create_sequence(result);
}

export function eval_sort_op(_ctx: ExpressionEnvironment, _expr: SortSegment, _sequence: Sequence): Sequence {
throw new Error('NOT IMPLEMENTED');
}

export function eval_index_op(ctx: ExpressionEnvironment, op: IndexSegment, sequence: Sequence): Sequence {
const output = [];
const output = create_sequence();

for (const value of sequence) {
const scope = { ...ctx };
const value_array = Array.isArray(value) ? value : [value];
for (let i = 0; i < value_array.length; i += 1) {
scope[op.symbol] = i;
const result = eval_path_sequence(scope, op.segments, [value_array[i]]);
const result = eval_path_sequence(scope, op.segments, create_sequence(value_array[i]));
if (result) {
output.push(result);
}
Expand All @@ -145,14 +153,14 @@ export function eval_context_op(ctx: ExpressionEnvironment, op: ContextSegment,
// for each result in the expression run the path sequence using the parent item as context and the result bound to the symbol
// concatenate all the sequence results into a single sequence

const output = [];
const output = create_sequence();

for (const item of sequence.flat()) {
const intermediate = eval_path_segment(ctx, op.expression, [item]);
const intermediate = eval_path_segment(ctx, op.expression, create_sequence(item));
const scope = { ...ctx };
for (const elem of intermediate.flat()) {
scope[op.symbol] = elem;
const result = eval_path_sequence(scope, op.segments, [item]);
const result = eval_path_sequence(scope, op.segments, create_sequence(item));
if (result) {
output.push(result);
}
Expand All @@ -162,13 +170,13 @@ export function eval_context_op(ctx: ExpressionEnvironment, op: ContextSegment,
}

export function eval_field_expr(expr: FieldExpression, value: SimpleValue): SimpleValue {
let sequence = [value];
let sequence = create_sequence(value);
sequence = eval_field_op(expr, sequence);
return flatten_sequence(sequence);
}

export function eval_wild_expr(descend: boolean, value: SimpleValue): SimpleValue {
let sequence = [value];
let sequence = create_sequence(value);
sequence = eval_wild_op(descend, sequence);
return flatten_sequence(sequence);
}
Expand All @@ -177,14 +185,15 @@ export function eval_parent_expr(): never {
throw new Error('NOT IMPLEMENTED');
}

export function eval_wild_op(descend: boolean, sequence: SimpleArray): SimpleArray {
let result: SimpleValue[] = [];
export function eval_wild_op(descend: boolean, sequence: Sequence): Sequence {
let result = create_sequence();

while (sequence.length) {
// pop value from stack
const next = sequence.pop()!;
if (Array.isArray(next)) {
// push back array items
sequence = sequence.concat(next);
sequence = concat_sequence(sequence, next);
}
else if (next instanceof Range || !next) {
// skip non-dictionary items
Expand All @@ -193,23 +202,26 @@ export function eval_wild_op(descend: boolean, sequence: SimpleArray): SimpleArr
else if (typeof next === 'object') {
const values = Object.values(next);
if (descend) {
sequence = sequence.concat(values);
sequence = concat_sequence(sequence, values);
}
// NOTE order of results might wrong, sorry
result = values.concat(result);
result = concat_sequence(values, result);
} else {
result.unshift(next);
}
}
return result;
}

export function eval_field_op(expr: FieldExpression, sequence: SimpleArray): SimpleArray {
const result: SimpleValue[] = [];
export function eval_field_op(expr: FieldExpression, sequence: Sequence): Sequence {
const result = create_sequence();

while (sequence.length) {
// pop value from stack
const next = sequence.pop()!;
if (Array.isArray(next)) {
// push back array items
sequence = sequence.concat(next);
sequence = concat_sequence(sequence, next);
}
else if (next instanceof Range || !next) {
// skip non-dictionary items
Expand All @@ -223,28 +235,30 @@ export function eval_field_op(expr: FieldExpression, sequence: SimpleArray): Sim
return result;
}

export function eval_generic_op(ctx: ExpressionEnvironment, expr: Expression, sequence: SimpleArray): SimpleArray {
const result: SimpleArray = [];
export function eval_generic_op(ctx: ExpressionEnvironment, expr: Expression, sequence: Sequence): Sequence {
const result = create_sequence();

for (const val of sequence.flat()) {
const el = eval_any_expr(ctx, expr, val);
if (el !== undefined) {
result.push(el);
result.push([el]);
}
}

return result;
}

export function flatten_sequence(sequence: SimpleArray): SimpleValue {
export function flatten_sequence(sequence: Sequence): SimpleValue {
if (sequence.length === 0) {
return undefined;
}

const flat = sequence = sequence.flat();
const flat = sequence.flat();

return flat.length === 1 ? flat[0] : flat;
}

export function* flatten(arr: SimpleArray): Iterable<SimpleValue> {
export function* flatten(arr: Sequence): Iterable<SimpleValue> {
while (arr.length) {
// pop value from stack
const next = arr.shift()!;
Expand Down

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