Symfony\Component\Yaml\Parser::parseBlockScalar PHP Method

    private function parseBlockScalar($style, $chomping = '', $indentation = 0)
    {
        $notEOF = $this->moveToNextLine();
        if (!$notEOF) {
            return '';
        }
        $isCurrentLineBlank = $this->isCurrentLineBlank();
        $blockLines = array();
        // leading blank lines are consumed before determining indentation
        while ($notEOF && $isCurrentLineBlank) {
            // newline only if not EOF
            if ($notEOF = $this->moveToNextLine()) {
                $blockLines[] = '';
                $isCurrentLineBlank = $this->isCurrentLineBlank();
            }
        }
        // determine indentation if not specified
        if (0 === $indentation) {
            if (preg_match('/^ +/', $this->currentLine, $matches)) {
                $indentation = strlen($matches[0]);
            }
        }
        if ($indentation > 0) {
            $pattern = sprintf('/^ {%d}(.*)$/', $indentation);
            while ($notEOF && ($isCurrentLineBlank || preg_match($pattern, $this->currentLine, $matches))) {
                if ($isCurrentLineBlank && strlen($this->currentLine) > $indentation) {
                    $blockLines[] = substr($this->currentLine, $indentation);
                } elseif ($isCurrentLineBlank) {
                    $blockLines[] = '';
                } else {
                    $blockLines[] = $matches[1];
                }
                // newline only if not EOF
                if ($notEOF = $this->moveToNextLine()) {
                    $isCurrentLineBlank = $this->isCurrentLineBlank();
                }
            }
        } elseif ($notEOF) {
            $blockLines[] = '';
        }
        if ($notEOF) {
            $blockLines[] = '';
            $this->moveToPreviousLine();
        } elseif (!$notEOF && !$this->isCurrentLineLastLineInDocument()) {
            $blockLines[] = '';
        }
        // folded style
        if ('>' === $style) {
            $text = '';
            $previousLineIndented = false;
            $previousLineBlank = false;
            for ($i = 0; $i < count($blockLines); ++$i) {
                if ('' === $blockLines[$i]) {
                    $text .= "\n";
                    $previousLineIndented = false;
                    $previousLineBlank = true;
                } elseif (' ' === $blockLines[$i][0]) {
                    $text .= "\n" . $blockLines[$i];
                    $previousLineIndented = true;
                    $previousLineBlank = false;
                } elseif ($previousLineIndented) {
                    $text .= "\n" . $blockLines[$i];
                    $previousLineIndented = false;
                    $previousLineBlank = false;
                } elseif ($previousLineBlank || 0 === $i) {
                    $text .= $blockLines[$i];
                    $previousLineIndented = false;
                    $previousLineBlank = false;
                } else {
                    $text .= ' ' . $blockLines[$i];
                    $previousLineIndented = false;
                    $previousLineBlank = false;
                }
            }
        } else {
            $text = implode("\n", $blockLines);
        }
        // deal with trailing newlines
        if ('' === $chomping) {
            $text = preg_replace('/\\n+$/', "\n", $text);
        } elseif ('-' === $chomping) {
            $text = preg_replace('/\\n+$/', '', $text);
        }
        return $text;
    }