static void outputInstructionStack()

in freemarker-core/src/main/java/freemarker/core/Environment.java [2620:2692]
72 lines of code
24 McCabe index (conditional complexity)

    static void outputInstructionStack(
            TemplateElement[] instructionStackSnapshot, boolean terseMode, Writer w) {
        final PrintWriter pw = (PrintWriter) (w instanceof PrintWriter ? w : null);
        try {
            if (instructionStackSnapshot != null) {
                final int totalFrames = instructionStackSnapshot.length;
                int framesToPrint = terseMode
                        ? (totalFrames <= TERSE_MODE_INSTRUCTION_STACK_TRACE_LIMIT
                                ? totalFrames
                                : TERSE_MODE_INSTRUCTION_STACK_TRACE_LIMIT - 1)
                        : totalFrames;
                boolean hideNestringRelatedFrames = terseMode && framesToPrint < totalFrames;
                int nestingRelatedFramesHidden = 0;
                int trailingFramesHidden = 0;
                int framesPrinted = 0;
                for (int frameIdx = 0; frameIdx < totalFrames; frameIdx++) {
                    TemplateElement stackEl = instructionStackSnapshot[frameIdx];
                    final boolean nestingRelatedElement = (frameIdx > 0 && stackEl instanceof BodyInstruction)
                            || (frameIdx > 1 && instructionStackSnapshot[frameIdx - 1] instanceof BodyInstruction);
                    if (framesPrinted < framesToPrint) {
                        if (!nestingRelatedElement || !hideNestringRelatedFrames) {
                            w.write(frameIdx == 0
                                    ? "\t- Failed at: "
                                    : (nestingRelatedElement
                                            ? "\t~ Reached through: "
                                            : "\t- Reached through: "));
                            w.write(instructionStackItemToString(stackEl));
                            if (pw != null) pw.println();
                            else
                                w.write('\n');
                            framesPrinted++;
                        } else {
                            nestingRelatedFramesHidden++;
                        }
                    } else {
                        trailingFramesHidden++;
                    }
                }

                boolean hadClosingNotes = false;
                if (trailingFramesHidden > 0) {
                    w.write("\t... (Had ");
                    w.write(String.valueOf(trailingFramesHidden + nestingRelatedFramesHidden));
                    w.write(" more, hidden for tersenes)");
                    hadClosingNotes = true;
                }
                if (nestingRelatedFramesHidden > 0) {
                    if (hadClosingNotes) {
                        w.write(' ');
                    } else {
                        w.write('\t');
                    }
                    w.write("(Hidden " + nestingRelatedFramesHidden + " \"~\" lines for terseness)");
                    if (pw != null) pw.println();
                    else
                        w.write('\n');
                    hadClosingNotes = true;
                }
                if (hadClosingNotes) {
                    if (pw != null) pw.println();
                    else
                        w.write('\n');
                }
            } else {
                w.write("(The stack was empty)");
                if (pw != null) pw.println();
                else
                    w.write('\n');
            }
        } catch (IOException e) {
            LOG.error("Failed to print FTL stack trace", e);
        }
    }