Henry
177b5596b5
Co-authored-by: nova28 <17953305+nova28@users.noreply.github.com> Co-authored-by: Carlos Florencio <carlosmflorencio@gmail.com>
97 lines
3.5 KiB
Go
97 lines
3.5 KiB
Go
package service
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import (
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"errors"
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"strings"
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"unicode"
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)
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// ErrPlanAppendFragmentWhitespaceOnly rejects an append fragment consisting
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// only of whitespace: such a fragment can only
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// add separator noise to a document from which it cannot be removed.
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var ErrPlanAppendFragmentWhitespaceOnly = errors.New("append fragment must contain a non-whitespace character")
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// ErrPlanContentReadFailed reports that an append could not read the stored
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// plan content it needed to compose against.
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// Deliberately distinct from ErrTaskPlanNotFound: reporting a read failure
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// as "not found" would send the caller to create_task_plan_kandev, which
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// upserts and commits the fragment as the entire plan — the destruction
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// this mode exists to prevent, reached through the error message. The
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// message carries no storage detail.
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var ErrPlanContentReadFailed = errors.New("could not read the current plan content; the append was not applied")
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// validateAppendFragment requires content and rejects a whitespace-only
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// fragment in an append request.
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func validateAppendFragment(content string) error {
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if content == "" {
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return ErrContentRequired
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}
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if isWhitespaceOnly(content) {
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return ErrPlanAppendFragmentWhitespaceOnly
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}
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return nil
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}
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// isWhitespaceOnly reports whether every rune in s has Unicode's
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// White_Space property, matching this capability's normative "whitespace"
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// definition (docs/specs/tasks/requirements/plan-write-append-mode.md
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// #terminology). An empty string is vacuously whitespace-only.
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func isWhitespaceOnly(s string) bool {
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for _, r := range s {
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if !unicode.IsSpace(r) {
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return false
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}
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}
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return true
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}
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// composePlanAppend implements the separator normalization in
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// docs/specs/tasks/system-design/plan-write-append-mode.md ("Separator
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// normalization"). The caller must have already rejected a whitespace-only
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// fragment via validateAppendFragment: this function does not re-check
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// that, and relies on it to guarantee trimLeadingBlankLines never consumes
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// fragment entirely.
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func composePlanAppend(stored, fragment string) string {
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trimmedStored := strings.TrimRightFunc(stored, unicode.IsSpace)
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trimmedFragment := trimLeadingBlankLines(fragment)
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if trimmedStored == "" {
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return trimmedFragment
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}
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return trimmedStored + "\n\n" + trimmedFragment
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}
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// trimLeadingBlankLines removes fragment's leading empty and
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// whitespace-only lines (a line's terminator is excluded from its own
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// whitespace check, per the requirements' "whitespace-only line"
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// definition), preserving leading spaces and tabs on the first line
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// containing a non-whitespace character and every character after it.
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func trimLeadingBlankLines(fragment string) string {
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rest := fragment
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for {
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line, lineLen, terminatorLen, hasMore := firstLine(rest)
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if !hasMore || !isWhitespaceOnly(line) {
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return rest
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}
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rest = rest[lineLen+terminatorLen:]
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}
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}
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// firstLine returns rest's first line's content (excluding its
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// terminator), that content's byte length, its terminator's byte length (1
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// for "\n", 2 for "\r\n"), and whether a terminator was found at all. When
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// hasMore is false, rest has no terminator and line/lineLen/terminatorLen
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// describe rest in its entirety.
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func firstLine(rest string) (line string, lineLen, terminatorLen int, hasMore bool) {
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idx := strings.IndexByte(rest, '\n')
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if idx == -1 {
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return rest, len(rest), 0, false
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}
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lineLen = idx
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terminatorLen = 1
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if idx > 0 && rest[idx-1] == '\r' {
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lineLen = idx - 1
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terminatorLen = 2
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}
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return rest[:lineLen], lineLen, terminatorLen, true
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}
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