forked from gitea/gitea
339 lines
9.5 KiB
Go
339 lines
9.5 KiB
Go
// Copyright 2020 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package gitgraph
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import (
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"bytes"
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"fmt"
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)
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// Parser represents a git graph parser. It is stateful containing the previous
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// glyphs, detected flows and color assignments.
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type Parser struct {
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glyphs []byte
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oldGlyphs []byte
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flows []int64
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oldFlows []int64
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maxFlow int64
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colors []int
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oldColors []int
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availableColors []int
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nextAvailable int
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firstInUse int
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firstAvailable int
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maxAllowedColors int
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}
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// Reset resets the internal parser state.
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func (parser *Parser) Reset() {
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parser.glyphs = parser.glyphs[0:0]
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parser.oldGlyphs = parser.oldGlyphs[0:0]
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parser.flows = parser.flows[0:0]
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parser.oldFlows = parser.oldFlows[0:0]
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parser.maxFlow = 0
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parser.colors = parser.colors[0:0]
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parser.oldColors = parser.oldColors[0:0]
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parser.availableColors = parser.availableColors[0:0]
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parser.availableColors = append(parser.availableColors, 1, 2)
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parser.nextAvailable = 0
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parser.firstInUse = -1
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parser.firstAvailable = 0
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parser.maxAllowedColors = 0
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}
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// AddLineToGraph adds the line as a row to the graph
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func (parser *Parser) AddLineToGraph(graph *Graph, row int, line []byte) error {
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idx := bytes.Index(line, []byte("DATA:"))
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if idx < 0 {
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parser.ParseGlyphs(line)
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} else {
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parser.ParseGlyphs(line[:idx])
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}
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var err error
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commitDone := false
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for column, glyph := range parser.glyphs {
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if glyph == ' ' {
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continue
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}
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flowID := parser.flows[column]
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graph.AddGlyph(row, column, flowID, parser.colors[column], glyph)
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if glyph == '*' {
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if commitDone {
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if err != nil {
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err = fmt.Errorf("double commit on line %d: %s. %w", row, string(line), err)
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} else {
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err = fmt.Errorf("double commit on line %d: %s", row, string(line))
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}
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}
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commitDone = true
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if idx < 0 {
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if err != nil {
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err = fmt.Errorf("missing data section on line %d with commit: %s. %w", row, string(line), err)
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} else {
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err = fmt.Errorf("missing data section on line %d with commit: %s", row, string(line))
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}
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continue
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}
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err2 := graph.AddCommit(row, column, flowID, line[idx+5:])
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if err != nil && err2 != nil {
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err = fmt.Errorf("%v %w", err2, err)
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continue
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} else if err2 != nil {
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err = err2
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continue
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}
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}
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}
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if !commitDone {
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graph.Commits = append(graph.Commits, RelationCommit)
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}
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return err
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}
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func (parser *Parser) releaseUnusedColors() {
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if parser.firstInUse > -1 {
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// Here we step through the old colors, searching for them in the
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// "in-use" section of availableColors (that is, the colors between
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// firstInUse and firstAvailable)
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// Ensure that the benchmarks are not worsened with proposed changes
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stepstaken := 0
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position := parser.firstInUse
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for _, color := range parser.oldColors {
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if color == 0 {
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continue
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}
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found := false
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i := position
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for j := stepstaken; i != parser.firstAvailable && j < len(parser.availableColors); j++ {
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colorToCheck := parser.availableColors[i]
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if colorToCheck == color {
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found = true
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break
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}
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i = (i + 1) % len(parser.availableColors)
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}
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if !found {
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// Duplicate color
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continue
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}
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// Swap them around
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parser.availableColors[position], parser.availableColors[i] = parser.availableColors[i], parser.availableColors[position]
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stepstaken++
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position = (parser.firstInUse + stepstaken) % len(parser.availableColors)
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if position == parser.firstAvailable || stepstaken == len(parser.availableColors) {
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break
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}
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}
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if stepstaken == len(parser.availableColors) {
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parser.firstAvailable = -1
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} else {
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parser.firstAvailable = position
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if parser.nextAvailable == -1 {
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parser.nextAvailable = parser.firstAvailable
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}
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}
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}
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}
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// ParseGlyphs parses the provided glyphs and sets the internal state
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func (parser *Parser) ParseGlyphs(glyphs []byte) {
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// Clean state for parsing this row
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parser.glyphs, parser.oldGlyphs = parser.oldGlyphs, parser.glyphs
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parser.glyphs = parser.glyphs[0:0]
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parser.flows, parser.oldFlows = parser.oldFlows, parser.flows
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parser.flows = parser.flows[0:0]
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parser.colors, parser.oldColors = parser.oldColors, parser.colors
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// Ensure we have enough flows and colors
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parser.colors = parser.colors[0:0]
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for range glyphs {
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parser.flows = append(parser.flows, 0)
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parser.colors = append(parser.colors, 0)
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}
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// Copy the provided glyphs in to state.glyphs for safekeeping
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parser.glyphs = append(parser.glyphs, glyphs...)
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// release unused colors
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parser.releaseUnusedColors()
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for i := len(glyphs) - 1; i >= 0; i-- {
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glyph := glyphs[i]
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switch glyph {
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case '|':
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fallthrough
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case '*':
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parser.setUpFlow(i)
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case '/':
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parser.setOutFlow(i)
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case '\\':
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parser.setInFlow(i)
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case '_':
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parser.setRightFlow(i)
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case '.':
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fallthrough
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case '-':
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parser.setLeftFlow(i)
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case ' ':
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// no-op
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default:
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parser.newFlow(i)
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}
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}
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}
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func (parser *Parser) takePreviousFlow(i, j int) {
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if j < len(parser.oldFlows) && parser.oldFlows[j] > 0 {
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parser.flows[i] = parser.oldFlows[j]
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parser.oldFlows[j] = 0
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parser.colors[i] = parser.oldColors[j]
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parser.oldColors[j] = 0
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} else {
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parser.newFlow(i)
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}
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}
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func (parser *Parser) takeCurrentFlow(i, j int) {
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if j < len(parser.flows) && parser.flows[j] > 0 {
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parser.flows[i] = parser.flows[j]
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parser.colors[i] = parser.colors[j]
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} else {
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parser.newFlow(i)
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}
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}
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func (parser *Parser) newFlow(i int) {
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parser.maxFlow++
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parser.flows[i] = parser.maxFlow
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// Now give this flow a color
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if parser.nextAvailable == -1 {
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next := len(parser.availableColors)
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if parser.maxAllowedColors < 1 || next < parser.maxAllowedColors {
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parser.nextAvailable = next
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parser.firstAvailable = next
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parser.availableColors = append(parser.availableColors, next+1)
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}
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}
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parser.colors[i] = parser.availableColors[parser.nextAvailable]
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if parser.firstInUse == -1 {
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parser.firstInUse = parser.nextAvailable
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}
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parser.availableColors[parser.firstAvailable], parser.availableColors[parser.nextAvailable] = parser.availableColors[parser.nextAvailable], parser.availableColors[parser.firstAvailable]
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parser.nextAvailable = (parser.nextAvailable + 1) % len(parser.availableColors)
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parser.firstAvailable = (parser.firstAvailable + 1) % len(parser.availableColors)
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if parser.nextAvailable == parser.firstInUse {
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parser.nextAvailable = parser.firstAvailable
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}
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if parser.nextAvailable == parser.firstInUse {
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parser.nextAvailable = -1
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parser.firstAvailable = -1
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}
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}
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// setUpFlow handles '|' or '*'
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func (parser *Parser) setUpFlow(i int) {
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// In preference order:
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//
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// Previous Row: '\? ' ' |' ' /'
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// Current Row: ' | ' ' |' ' | '
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if i > 0 && i-1 < len(parser.oldGlyphs) && parser.oldGlyphs[i-1] == '\\' {
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parser.takePreviousFlow(i, i-1)
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} else if i < len(parser.oldGlyphs) && (parser.oldGlyphs[i] == '|' || parser.oldGlyphs[i] == '*') {
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parser.takePreviousFlow(i, i)
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} else if i+1 < len(parser.oldGlyphs) && parser.oldGlyphs[i+1] == '/' {
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parser.takePreviousFlow(i, i+1)
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} else {
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parser.newFlow(i)
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}
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}
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// setOutFlow handles '/'
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func (parser *Parser) setOutFlow(i int) {
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// In preference order:
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//
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// Previous Row: ' |/' ' |_' ' |' ' /' ' _' '\'
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// Current Row: '/| ' '/| ' '/ ' '/ ' '/ ' '/'
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if i+2 < len(parser.oldGlyphs) &&
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(parser.oldGlyphs[i+1] == '|' || parser.oldGlyphs[i+1] == '*') &&
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(parser.oldGlyphs[i+2] == '/' || parser.oldGlyphs[i+2] == '_') &&
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i+1 < len(parser.glyphs) &&
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(parser.glyphs[i+1] == '|' || parser.glyphs[i+1] == '*') {
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parser.takePreviousFlow(i, i+2)
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} else if i+1 < len(parser.oldGlyphs) &&
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(parser.oldGlyphs[i+1] == '|' || parser.oldGlyphs[i+1] == '*' ||
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parser.oldGlyphs[i+1] == '/' || parser.oldGlyphs[i+1] == '_') {
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parser.takePreviousFlow(i, i+1)
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if parser.oldGlyphs[i+1] == '/' {
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parser.glyphs[i] = '|'
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}
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} else if i < len(parser.oldGlyphs) && parser.oldGlyphs[i] == '\\' {
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parser.takePreviousFlow(i, i)
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} else {
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parser.newFlow(i)
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}
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}
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// setInFlow handles '\'
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func (parser *Parser) setInFlow(i int) {
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// In preference order:
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//
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// Previous Row: '| ' '-. ' '| ' '\ ' '/' '---'
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// Current Row: '|\' ' \' ' \' ' \' '\' ' \ '
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if i > 0 && i-1 < len(parser.oldGlyphs) &&
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(parser.oldGlyphs[i-1] == '|' || parser.oldGlyphs[i-1] == '*') &&
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(parser.glyphs[i-1] == '|' || parser.glyphs[i-1] == '*') {
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parser.newFlow(i)
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} else if i > 0 && i-1 < len(parser.oldGlyphs) &&
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(parser.oldGlyphs[i-1] == '|' || parser.oldGlyphs[i-1] == '*' ||
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parser.oldGlyphs[i-1] == '.' || parser.oldGlyphs[i-1] == '\\') {
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parser.takePreviousFlow(i, i-1)
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if parser.oldGlyphs[i-1] == '\\' {
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parser.glyphs[i] = '|'
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}
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} else if i < len(parser.oldGlyphs) && parser.oldGlyphs[i] == '/' {
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parser.takePreviousFlow(i, i)
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} else {
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parser.newFlow(i)
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}
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}
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// setRightFlow handles '_'
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func (parser *Parser) setRightFlow(i int) {
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// In preference order:
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//
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// Current Row: '__' '_/' '_|_' '_|/'
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if i+1 < len(parser.glyphs) &&
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(parser.glyphs[i+1] == '_' || parser.glyphs[i+1] == '/') {
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parser.takeCurrentFlow(i, i+1)
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} else if i+2 < len(parser.glyphs) &&
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(parser.glyphs[i+1] == '|' || parser.glyphs[i+1] == '*') &&
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(parser.glyphs[i+2] == '_' || parser.glyphs[i+2] == '/') {
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parser.takeCurrentFlow(i, i+2)
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} else {
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parser.newFlow(i)
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}
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}
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// setLeftFlow handles '----.'
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func (parser *Parser) setLeftFlow(i int) {
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if parser.glyphs[i] == '.' {
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parser.newFlow(i)
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} else if i+1 < len(parser.glyphs) &&
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(parser.glyphs[i+1] == '-' || parser.glyphs[i+1] == '.') {
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parser.takeCurrentFlow(i, i+1)
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} else {
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parser.newFlow(i)
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}
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}
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