Add markdown parser

34 files changed, 870 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b63da45
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,42 @@
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### IntelliJ IDEA ###
+.idea/modules.xml
+.idea/jarRepositories.xml
+.idea/compiler.xml
+.idea/libraries/
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
\ No newline at end of file
diff --git a/build.gradle.kts b/build.gradle.kts
new file mode 100644
index 0000000..5081342
--- /dev/null
+++ b/build.gradle.kts
@@ -0,0 +1,22 @@
+plugins {
+    kotlin("jvm") version "1.9.22"
+}
+
+group = "org.example"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation("org.jetbrains:markdown:0.5.0")
+    testImplementation("org.jetbrains.kotlin:kotlin-test")
+}
+
+tasks.test {
+    useJUnitPlatform()
+}
+kotlin {
+    jvmToolchain(17)
+}
\ No newline at end of file
diff --git a/data/test.md b/data/test.md
new file mode 100644
index 0000000..ccd4932
--- /dev/null
+++ b/data/test.md
@@ -0,0 +1,9 @@
+# Hello World
+
+***lol*  hehe**
+
+```java
+public class ObjectControllerFactoryManagerProvider<T extends ObjectControllerFactoryManager<T>> {
+    
+}
+```
\ No newline at end of file
diff --git a/gradle.properties b/gradle.properties
new file mode 100644
index 0000000..7fc6f1f
--- /dev/null
+++ b/gradle.properties
@@ -0,0 +1 @@
+kotlin.code.style=official
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..7f93135
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.jar
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..3fa8f86
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
new file mode 100755
index 0000000..1aa94a4
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,249 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..93e3f59
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/settings.gradle.kts b/settings.gradle.kts
new file mode 100644
index 0000000..ec04c91
--- /dev/null
+++ b/settings.gradle.kts
@@ -0,0 +1,2 @@
+rootProject.name = "blog"
+
diff --git a/src/main/kotlin/moe/nea/blog/md/Begin.kt b/src/main/kotlin/moe/nea/blog/md/Begin.kt
new file mode 100644
index 0000000..482c114
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Begin.kt
@@ -0,0 +1,8 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+class Begin : MarkdownFormat {
+    override fun debugFormat(printStream: PrintStream) {
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/BlockParser.kt b/src/main/kotlin/moe/nea/blog/md/BlockParser.kt
new file mode 100644
index 0000000..2ca812f
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/BlockParser.kt
@@ -0,0 +1,7 @@
+package moe.nea.blog.md
+
+interface BlockParser {
+    fun detect(line: String): Boolean
+    fun parse(parser: MarkdownParser): MarkdownBlock
+    val prio: Int
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/BlogPost.kt b/src/main/kotlin/moe/nea/blog/md/BlogPost.kt
new file mode 100644
index 0000000..25ec13f
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/BlogPost.kt
@@ -0,0 +1,11 @@
+package moe.nea.blog.md
+
+import java.io.File
+
+
+fun main() {
+    val parser = MarkdownParser(File("data/test.md").readText())
+    parser.addDefaultParsers()
+    val doc = parser.readDocument()
+    doc.debugFormat(System.out)
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/Bold.kt b/src/main/kotlin/moe/nea/blog/md/Bold.kt
new file mode 100644
index 0000000..aa46622
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Bold.kt
@@ -0,0 +1,11 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+data class Bold(val inner: MarkdownFormat) : MarkdownFormat {
+    override fun debugFormat(printStream: PrintStream) {
+        printStream.print("<b>")
+        inner.debugFormat(printStream)
+        printStream.print("</b>")
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/CodeBlock.kt b/src/main/kotlin/moe/nea/blog/md/CodeBlock.kt
new file mode 100644
index 0000000..2882b77
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/CodeBlock.kt
@@ -0,0 +1,18 @@
+package moe.nea.blog.md
+
+import moe.nea.blog.util.indent
+import java.io.PrintStream
+
+data class CodeBlock(val language: String, val lines: List<String>) : MarkdownBlock {
+    override fun debugFormat(indent: Int, printStream: PrintStream) {
+        printStream.indent(indent)
+        printStream.println("<code lang=$language>")
+        lines.forEach {
+            printStream.indent(indent)
+            printStream.println(it)
+        }
+        printStream.indent(indent)
+        printStream.println("</code>")
+    }
+}
+
diff --git a/src/main/kotlin/moe/nea/blog/md/CodeBlockParser.kt b/src/main/kotlin/moe/nea/blog/md/CodeBlockParser.kt
new file mode 100644
index 0000000..0c894fe
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/CodeBlockParser.kt
@@ -0,0 +1,23 @@
+package moe.nea.blog.md
+
+object CodeBlockParser : BlockParser {
+    override fun detect(line: String): Boolean {
+        return line.startsWith("```")
+    }
+
+    override fun parse(parser: MarkdownParser): MarkdownBlock {
+        val language = parser.consumeLine()!!.removePrefix("```")
+        val lines = mutableListOf<String>()
+        while (true) {
+            val line = parser.consumeLine() ?: error("Unfinished code block")
+            if (line == "```")
+                break
+            lines.add(line)
+        }
+        return CodeBlock(language, lines)
+    }
+
+    override val prio: Int
+        get() = 10
+
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/Document.kt b/src/main/kotlin/moe/nea/blog/md/Document.kt
new file mode 100644
index 0000000..ce83ef1
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Document.kt
@@ -0,0 +1,11 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+data class Document(
+    val list: List<MarkdownBlock>
+) : MarkdownElement {
+    fun debugFormat(printStream: PrintStream) {
+        list.forEach { it.debugFormat(0, printStream) }
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/FormatSequence.kt b/src/main/kotlin/moe/nea/blog/md/FormatSequence.kt
new file mode 100644
index 0000000..94b55b9
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/FormatSequence.kt
@@ -0,0 +1,11 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+data class FormatSequence(val list: List<MarkdownFormat>) : MarkdownFormat {
+    constructor(vararg list: MarkdownFormat) : this(list.toList())
+
+    override fun debugFormat(printStream: PrintStream) {
+        list.forEach { it.debugFormat(printStream) }
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/Header.kt b/src/main/kotlin/moe/nea/blog/md/Header.kt
new file mode 100644
index 0000000..fab2306
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Header.kt
@@ -0,0 +1,11 @@
+package moe.nea.blog.md
+
+import moe.nea.blog.util.indent
+import java.io.PrintStream
+
+data class Header(val level: Int, val text: String) : MarkdownBlock {
+    override fun debugFormat(indent: Int, printStream: PrintStream) {
+        printStream.indent(indent)
+        printStream.println("header level=$level: $text")
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/HeaderParser.kt b/src/main/kotlin/moe/nea/blog/md/HeaderParser.kt
new file mode 100644
index 0000000..928cf58
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/HeaderParser.kt
@@ -0,0 +1,17 @@
+package moe.nea.blog.md
+
+object HeaderParser : BlockParser {
+    override fun detect(line: String): Boolean {
+        return line.matches("#+ .*".toRegex())
+    }
+
+    override fun parse(parser: MarkdownParser): MarkdownBlock {
+        val line = parser.consumeLine()!!
+        val level = line.indexOf(" ")
+        val text = line.substring(level).trim()
+        return Header(level, text)
+    }
+
+    override val prio: Int
+        get() = 10
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/InlineParser.kt b/src/main/kotlin/moe/nea/blog/md/InlineParser.kt
new file mode 100644
index 0000000..4b60963
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/InlineParser.kt
@@ -0,0 +1,7 @@
+package moe.nea.blog.md
+
+interface InlineParser {
+    fun detect(lookback: MarkdownFormat, rest: String): Boolean
+    val specialSyntax: Set<Char>
+    fun parse(parser: MarkdownParser, text: String): Pair<MarkdownFormat, String>
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/Italics.kt b/src/main/kotlin/moe/nea/blog/md/Italics.kt
new file mode 100644
index 0000000..47d8db2
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Italics.kt
@@ -0,0 +1,11 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+data class Italics(val inner: MarkdownFormat) : MarkdownFormat {
+    override fun debugFormat(printStream: PrintStream) {
+        printStream.print("<i>")
+        inner.debugFormat(printStream)
+        printStream.print("</i>")
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/ItalicsParser.kt b/src/main/kotlin/moe/nea/blog/md/ItalicsParser.kt
new file mode 100644
index 0000000..afecf79
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/ItalicsParser.kt
@@ -0,0 +1,91 @@
+package moe.nea.blog.md
+
+object ItalicsParser : InlineParser {
+    override fun detect(lookback: MarkdownFormat, rest: String): Boolean {
+        return lookback is Whitespace && "\\*+[^ ].*".toRegex().matches(rest)
+    }
+
+    override val specialSyntax: Set<Char>
+        get() = setOf('*')
+
+    override fun parse(parser: MarkdownParser, text: String): Pair<MarkdownFormat, String> {
+        var firstStarCount = 0
+        while (firstStarCount in text.indices) {
+            if (text[firstStarCount] != '*') break
+            firstStarCount++
+        }
+
+        if (firstStarCount < 1 || firstStarCount > 3) error("Invalid italics/bold sequence")
+
+        val isBold = firstStarCount >= 2
+        val isItalics = (firstStarCount % 2) == 1
+
+        val firstSequence = mutableListOf<MarkdownFormat>()
+        var remainingText = text.substring(firstStarCount)
+        var lastToken: MarkdownFormat = Begin() // TODO: dedicated begin token
+        while (true) {
+            val (element, next) = parser.parseInlineTextOnce(lastToken, remainingText)
+            remainingText = next
+            lastToken = element
+            firstSequence.add(element)
+            if (element !is Whitespace && next.startsWith("*")) break
+        }
+
+        var secondStarCount = 0
+        while (secondStarCount in remainingText.indices) {
+            if (remainingText[secondStarCount] != '*') break
+            secondStarCount++
+        }
+
+        if (secondStarCount > firstStarCount)
+            secondStarCount = firstStarCount
+        if (secondStarCount < 1) error("Invalid italics/bold sequence")
+
+        remainingText = remainingText.substring(secondStarCount)
+        var firstElement = parser.collapseInlineFormat(firstSequence)
+        if (secondStarCount == 2)
+            firstElement = Bold(firstElement)
+        if (secondStarCount == 1)
+            firstElement = Italics(firstElement)
+        if (secondStarCount == firstStarCount) {
+            if (isBold)
+                firstElement = Bold(firstElement)
+            if (isItalics)
+                firstElement = Italics(firstElement)
+            return Pair(firstElement, remainingText)
+        }
+
+        val secondSequence = mutableListOf<MarkdownFormat>()
+        lastToken = Begin()
+        while (true) {
+            val (element, next) = parser.parseInlineTextOnce(lastToken, remainingText)
+            remainingText = next
+            lastToken = element
+            secondSequence.add(element)
+            if (element !is Whitespace && next.startsWith("*")) break
+        }
+
+        var thirdStarCount = 0
+        while (thirdStarCount in remainingText.indices) {
+            if (remainingText[thirdStarCount] != '*') break
+            thirdStarCount++
+        }
+
+        if (thirdStarCount > firstStarCount - secondStarCount)
+            thirdStarCount = firstStarCount
+
+        remainingText = remainingText.substring(thirdStarCount)
+
+        if (thirdStarCount != firstStarCount - secondStarCount) {
+            error("Invalid italics/bold sequence")
+        }
+        var secondElement = parser.collapseInlineFormat(secondSequence)
+        var combined: MarkdownFormat = FormatSequence(firstElement, secondElement)
+        if (thirdStarCount == 1)
+            combined = Italics(combined)
+        if (thirdStarCount == 2)
+            combined = Bold(combined)
+        return Pair(combined, remainingText)
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/Link.kt b/src/main/kotlin/moe/nea/blog/md/Link.kt
new file mode 100644
index 0000000..f8fc858
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Link.kt
@@ -0,0 +1,11 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+data class Link(val label: MarkdownFormat?, val target: String) : MarkdownFormat {
+    override fun debugFormat(printStream: PrintStream) {
+        printStream.print("<link target=$target>")
+        label?.debugFormat(printStream)
+        printStream.print("</link>")
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/MarkdownBlock.kt b/src/main/kotlin/moe/nea/blog/md/MarkdownBlock.kt
new file mode 100644
index 0000000..fc432ef
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/MarkdownBlock.kt
@@ -0,0 +1,7 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+interface MarkdownBlock : MarkdownElement {
+    fun debugFormat(indent: Int, printStream: PrintStream)
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/MarkdownElement.kt b/src/main/kotlin/moe/nea/blog/md/MarkdownElement.kt
new file mode 100644
index 0000000..74aac6d
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/MarkdownElement.kt
@@ -0,0 +1,3 @@
+package moe.nea.blog.md
+
+interface MarkdownElement {}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/MarkdownFormat.kt b/src/main/kotlin/moe/nea/blog/md/MarkdownFormat.kt
new file mode 100644
index 0000000..d647854
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/MarkdownFormat.kt
@@ -0,0 +1,7 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+interface MarkdownFormat : MarkdownElement {
+    fun debugFormat(printStream: PrintStream)
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/MarkdownParser.kt b/src/main/kotlin/moe/nea/blog/md/MarkdownParser.kt
new file mode 100644
index 0000000..86b92d2
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/MarkdownParser.kt
@@ -0,0 +1,96 @@
+package moe.nea.blog.md
+
+import moe.nea.blog.util.indentSize
+import java.util.*
+
+
+class MarkdownParser(source: String) {
+    private val lines = source.lines()
+    private var lineIndex = 0
+    private var blockIndents = 0
+    private val indentStack = Stack<Int>()
+
+    private val blockParsers = mutableListOf<BlockParser>()
+    private val inlineParsers = mutableListOf<InlineParser>()
+
+    fun findParserFor(line: String): BlockParser? {
+        return blockParsers.filter { it.detect(line) }
+            .maxByOrNull { it.prio }
+    }
+
+    fun readChildBlock(): MarkdownBlock? {
+        val peek = peekLine() ?: return null
+        val blockParser = findParserFor(peek) ?: ParagraphParser
+        return blockParser.parse(this)
+    }
+
+    fun pushIndent(newIndent: Int) {
+        require(newIndent > blockIndents)
+        indentStack.push(blockIndents)
+        blockIndents = newIndent
+    }
+
+    fun popIndent() {
+        blockIndents = indentStack.pop()
+    }
+
+    fun consumeLine(): String? {
+        val line = peekLine()
+        if (line != null)
+            lineIndex++
+        return line
+    }
+
+    fun peekLine(): String? {
+        if (lineIndex !in lines.indices) return null
+        val line = lines[lineIndex]
+        val indent = line.indentSize()
+        if (indent != null && indent < blockIndents)
+            return null
+        return line.substring(blockIndents)
+    }
+
+    fun parseInlineTextOnce(lookback: MarkdownFormat, text: String): Pair<MarkdownFormat, String> {
+        val parser = inlineParsers.find { it.detect(lookback, text) }
+        if (parser != null)
+            return parser.parse(this, text)
+        require(!text.isEmpty()) // TODO handle empty string
+        if (text[0] == ' ')
+            return Pair(Whitespace(), text.substring(1))
+        val nextSpecial = text.indexOfFirst { it in inlineParsers.flatMap { it.specialSyntax } || it == ' ' }
+        return Pair(Word(text.substring(0, nextSpecial)), text.substring(nextSpecial))
+    }
+
+    fun parseInlineText(text: String): MarkdownFormat {
+        val seq = mutableListOf<MarkdownFormat>()
+        var remaining = text
+        var lastToken: MarkdownFormat = Begin()
+        while (remaining.isNotEmpty()) {
+            val (tok, next) = parseInlineTextOnce(lastToken, remaining)
+            seq.add(tok)
+            lastToken = tok
+            remaining = next
+        }
+        return collapseInlineFormat(seq)
+    }
+
+    fun collapseInlineFormat(sequence: List<MarkdownFormat>): MarkdownFormat {
+        return FormatSequence(sequence)
+    }
+
+    fun readDocument(): Document {
+        val list = mutableListOf<MarkdownBlock>()
+        while (true) {
+            val block = readChildBlock() ?: break
+            list.add(block)
+        }
+        return Document(list)
+    }
+
+    fun addDefaultParsers() {
+        blockParsers.add(CodeBlockParser)
+        blockParsers.add(HeaderParser)
+        inlineParsers.add(ItalicsParser)
+    }
+}
+
diff --git a/src/main/kotlin/moe/nea/blog/md/Paragraph.kt b/src/main/kotlin/moe/nea/blog/md/Paragraph.kt
new file mode 100644
index 0000000..54f688b
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Paragraph.kt
@@ -0,0 +1,12 @@
+package moe.nea.blog.md
+
+import moe.nea.blog.util.indent
+import java.io.PrintStream
+
+data class Paragraph(val format: MarkdownFormat) : MarkdownBlock {
+    override fun debugFormat(indent: Int, printStream: PrintStream) {
+        printStream.indent(indent)
+        format.debugFormat(printStream)
+        printStream.println()
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/ParagraphParser.kt b/src/main/kotlin/moe/nea/blog/md/ParagraphParser.kt
new file mode 100644
index 0000000..328c49b
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/ParagraphParser.kt
@@ -0,0 +1,31 @@
+package moe.nea.blog.md
+
+object ParagraphParser : BlockParser {
+    override fun detect(line: String): Boolean {
+        return true
+    }
+
+    override fun parse(parser: MarkdownParser): MarkdownBlock {
+        var text = ""
+        var emptyLineCount = 0
+        while (true) {
+            val line = parser.peekLine() ?: break
+            if (parser.findParserFor(line) != null) break
+            val trimmedLine = parser.consumeLine()!!.trim()
+            if (trimmedLine == "") {
+                emptyLineCount++
+            } else {
+                emptyLineCount = 0
+            }
+            if (emptyLineCount == 2) {
+                break
+            }
+            text += " $trimmedLine"
+        }
+        return Paragraph(parser.parseInlineText(text))
+    }
+
+    override val prio: Int
+        get() = -10
+
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/Text.kt b/src/main/kotlin/moe/nea/blog/md/Text.kt
new file mode 100644
index 0000000..fb89ff3
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Text.kt
@@ -0,0 +1,9 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+data class Text(val text: String) : MarkdownFormat {
+    override fun debugFormat(printStream: PrintStream) {
+        printStream.print(printStream)
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/Whitespace.kt b/src/main/kotlin/moe/nea/blog/md/Whitespace.kt
new file mode 100644
index 0000000..6a44152
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Whitespace.kt
@@ -0,0 +1,9 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+class Whitespace : MarkdownFormat {
+    override fun debugFormat(printStream: PrintStream) {
+        printStream.print(" ")
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/md/Word.kt b/src/main/kotlin/moe/nea/blog/md/Word.kt
new file mode 100644
index 0000000..ff89af5
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/md/Word.kt
@@ -0,0 +1,9 @@
+package moe.nea.blog.md
+
+import java.io.PrintStream
+
+data class Word(val text: String) : MarkdownFormat {
+    override fun debugFormat(printStream: PrintStream) {
+        printStream.print(text)
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/util/Indent.kt b/src/main/kotlin/moe/nea/blog/util/Indent.kt
new file mode 100644
index 0000000..5a61a48
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/util/Indent.kt
@@ -0,0 +1,5 @@
+package moe.nea.blog.util
+
+fun Appendable.indent(indent: Int) {
+    append(" ".repeat(indent))
+}
\ No newline at end of file
diff --git a/src/main/kotlin/moe/nea/blog/util/IndentSize.kt b/src/main/kotlin/moe/nea/blog/util/IndentSize.kt
new file mode 100644
index 0000000..de6a91a
--- /dev/null
+++ b/src/main/kotlin/moe/nea/blog/util/IndentSize.kt
@@ -0,0 +1,10 @@
+package moe.nea.blog.util
+
+fun String.indentSize(): Int? {
+    var i = 0
+    while (i in indices) {
+        if (this[i] != ' ') return i
+        i++
+    }
+    return null
+}
\ No newline at end of file