From 476f083fc0d4ac31da918f7e1110cabc10acf02f Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Sat, 11 Jul 2015 15:51:12 -0700
Subject: Factored out common bits of rendering into separate render module.

* Added render.c, render.h.
* Moved common functions and definitions from latex.c and commonmark.c
  to render.c, render.h.
* Added a wrapper, cmark_render, that creates a renderer given a
  character-escaper and a node renderer.

Closes #63.
---
 src/CMakeLists.txt |   2 +
 src/commonmark.c   | 234 +++++------------------------
 src/latex.c        | 434 +++++++++++++++++++----------------------------------
 src/render.c       | 186 +++++++++++++++++++++++
 src/render.h       |  67 +++++++++
 5 files changed, 445 insertions(+), 478 deletions(-)
 create mode 100644 src/render.c
 create mode 100644 src/render.h

(limited to 'src')

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index d8e57af..eee9316 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -15,6 +15,7 @@ set(HEADERS
   inlines.h
   houdini.h
   cmark_ctype.h
+  render.h
   )
 set(LIBRARY_SOURCES
   cmark.c
@@ -27,6 +28,7 @@ set(LIBRARY_SOURCES
   utf8.c
   buffer.c
   references.c
+  render.c
   man.c
   xml.c
   html.c
diff --git a/src/commonmark.c b/src/commonmark.c
index 9ad9137..c6a13e8 100644
--- a/src/commonmark.c
+++ b/src/commonmark.c
@@ -10,182 +10,51 @@
 #include "buffer.h"
 #include "utf8.h"
 #include "scanners.h"
+#include "render.h"
 
 // Functions to convert cmark_nodes to commonmark strings.
 
-struct render_state {
-	int options;
-	cmark_strbuf* buffer;
-	cmark_strbuf* prefix;
-	int column;
-	int width;
-	int need_cr;
-	bufsize_t last_breakable;
-	bool begin_line;
-	bool no_wrap;
-	bool in_tight_list_item;
-};
-
-static inline void cr(struct render_state *state)
+static inline void outc(cmark_render_state *state,
+			cmark_escaping escape,
+			int32_t c,
+			unsigned char nextc)
 {
-	if (state->need_cr < 1) {
-		state->need_cr = 1;
-	}
-}
-
-static inline void blankline(struct render_state *state)
-{
-	if (state->need_cr < 2) {
-		state->need_cr = 2;
-	}
-}
-
-typedef enum  {
-	LITERAL,
-	NORMAL,
-	TITLE,
-	URL
-} escaping;
-
-static inline bool
-needs_escaping(escaping escape,
-               int32_t c,
-               unsigned char next_c,
-               struct render_state *state)
-{
-	if (escape == NORMAL) {
-		return (c == '*' || c == '_' || c == '[' || c == ']' ||
-		        c == '<' || c == '>' || c == '\\' || c == '`' ||
-		        (c == '&' && isalpha(next_c)) ||
-		        (c == '!' && next_c == '[') ||
-		        (state->begin_line &&
-		         (c == '-' || c == '+' || c == '#' || c == '=')) ||
-		        (c == '#' && (isspace(next_c) || next_c == '\0')) ||
-		        ((c == '.' || c == ')') &&
-		         isdigit(state->buffer->ptr[state->buffer->size - 1])));
-	} else if (escape == TITLE) {
-		return (c == '`' || c == '<' || c == '>' || c == '"' ||
-		        c == '\\');
-	} else if (escape == URL) {
-		return (c == '`' || c == '<' || c == '>' || isspace(c) ||
-		        c == '\\' || c == ')' || c == '(');
-	} else {
-		return false;
-	}
-}
-
-static inline void out(struct render_state *state,
-                       cmark_chunk str,
-                       bool wrap,
-                       escaping escape)
-{
-	unsigned char* source = str.data;
-	int length = str.len;
-	unsigned char nextc;
-	int32_t c;
-	int i = 0;
-	int len;
-	cmark_chunk remainder = cmark_chunk_literal("");
-	int k = state->buffer->size - 1;
-
-	wrap = wrap && !state->no_wrap;
-
-	if (state->in_tight_list_item && state->need_cr > 1) {
-		state->need_cr = 1;
-	}
-	while (state->need_cr) {
-		if (k < 0 || state->buffer->ptr[k] == '\n') {
-			k -= 1;
-		} else {
-			cmark_strbuf_putc(state->buffer, '\n');
-			if (state->need_cr > 1) {
-				cmark_strbuf_put(state->buffer, state->prefix->ptr,
-				                 state->prefix->size);
-			}
-		}
-		state->column = 0;
-		state->begin_line = true;
-		state->need_cr -= 1;
-	}
-
-	while (i < length) {
-		if (state->begin_line) {
-			cmark_strbuf_put(state->buffer, state->prefix->ptr,
-			                 state->prefix->size);
-			// note: this assumes prefix is ascii:
-			state->column = state->prefix->size;
-		}
-
-		len = utf8proc_iterate(source + i, length - i, &c);
-		if (len == -1) { // error condition
-			return;  // return without rendering rest of string
-		}
-		nextc = source[i + len];
-		if (c == 32 && wrap) {
-			if (!state->begin_line) {
-				cmark_strbuf_putc(state->buffer, ' ');
-				state->column += 1;
-				state->begin_line = false;
-				state->last_breakable = state->buffer->size -
-				                        1;
-				// skip following spaces
-				while (source[i + 1] == ' ') {
-					i++;
-				}
-			}
-
-		} else if (c == 10) {
-			cmark_strbuf_putc(state->buffer, '\n');
-			state->column = 0;
-			state->begin_line = true;
-			state->last_breakable = 0;
-		} else if (needs_escaping(escape, c, nextc, state)) {
-			if (isspace(c)) {
-				// use percent encoding for spaces
-				cmark_strbuf_printf(state->buffer, "%%%2x", c);
-				state->column += 3;
-			} else {
-				cmark_strbuf_putc(state->buffer, '\\');
-				utf8proc_encode_char(c, state->buffer);
-				state->column += 2;
-			}
-			state->begin_line = false;
+	bool needs_escaping = false;
+	needs_escaping =
+		escape != LITERAL &&
+		((escape == NORMAL &&
+		  (c == '*' || c == '_' || c == '[' || c == ']' ||
+		   c == '<' || c == '>' || c == '\\' || c == '`' ||
+		   (c == '&' && isalpha(nextc)) ||
+		   (c == '!' && nextc == '[') ||
+		   (state->begin_line &&
+		    (c == '-' || c == '+' || c == '#' || c == '=')) ||
+		   ((c == '.' || c == ')') &&
+		    isdigit(state->buffer->ptr[state->buffer->size - 1])))) ||
+		 (escape == URL &&
+		  (c == '`' || c == '<' || c == '>' || isspace(c) ||
+		        c == '\\' || c == ')' || c == '(')) ||
+		 (escape == TITLE &&
+		  (c == '`' || c == '<' || c == '>' || c == '"' ||
+		        c == '\\')));
+
+	if (needs_escaping) {
+		if (isspace(c)) {
+			// use percent encoding for spaces
+			cmark_strbuf_printf(state->buffer, "%%%2x", c);
+			state->column += 3;
 		} else {
+			cmark_strbuf_putc(state->buffer, '\\');
 			utf8proc_encode_char(c, state->buffer);
-			state->column += 1;
-			state->begin_line = false;
+			state->column += 2;
 		}
-
-		// If adding the character went beyond width, look for an
-		// earlier place where the line could be broken:
-		if (state->width > 0 &&
-		    state->column > state->width &&
-		    !state->begin_line &&
-		    state->last_breakable > 0) {
-
-			// copy from last_breakable to remainder
-			cmark_chunk_set_cstr(&remainder, (char *) state->buffer->ptr + state->last_breakable + 1);
-			// truncate at last_breakable
-			cmark_strbuf_truncate(state->buffer, state->last_breakable);
-			// add newline, prefix, and remainder
-			cmark_strbuf_putc(state->buffer, '\n');
-			cmark_strbuf_put(state->buffer, state->prefix->ptr,
-			                 state->prefix->size);
-			cmark_strbuf_put(state->buffer, remainder.data, remainder.len);
-			state->column = state->prefix->size + remainder.len;
-			cmark_chunk_free(&remainder);
-			state->last_breakable = 0;
-			state->begin_line = false;
-		}
-
-		i += len;
+		state->begin_line = false;
+	} else {
+		utf8proc_encode_char(c, state->buffer);
+		state->column += 1;
+		state->begin_line = false;
 	}
-}
 
-static void lit(struct render_state *state, char *s, bool wrap)
-{
-	cmark_chunk str = cmark_chunk_literal(s);
-	out(state, str, wrap, LITERAL);
 }
 
 static int
@@ -287,7 +156,7 @@ get_containing_block(cmark_node *node)
 
 static int
 S_render_node(cmark_node *node, cmark_event_type ev_type,
-              struct render_state *state)
+              cmark_render_state *state)
 {
 	cmark_node *tmp;
 	cmark_chunk *code;
@@ -586,32 +455,5 @@ S_render_node(cmark_node *node, cmark_event_type ev_type,
 
 char *cmark_render_commonmark(cmark_node *root, int options, int width)
 {
-	char *result;
-	cmark_strbuf commonmark = GH_BUF_INIT;
-	cmark_strbuf prefix = GH_BUF_INIT;
-	if (CMARK_OPT_HARDBREAKS & options) {
-		width = 0;
-	}
-	struct render_state state = {
-		options, &commonmark, &prefix, 0, width,
-		0, 0, true, false, false
-	};
-	cmark_node *cur;
-	cmark_event_type ev_type;
-	cmark_iter *iter = cmark_iter_new(root);
-
-	while ((ev_type = cmark_iter_next(iter)) != CMARK_EVENT_DONE) {
-		cur = cmark_iter_get_node(iter);
-		if (!S_render_node(cur, ev_type, &state)) {
-			// a false value causes us to skip processing
-			// the node's contents.  this is used for
-			// autolinks.
-			cmark_iter_reset(iter, cur, CMARK_EVENT_EXIT);
-		}
-	}
-	result = (char *)cmark_strbuf_detach(&commonmark);
-
-	cmark_strbuf_free(&prefix);
-	cmark_iter_free(iter);
-	return result;
+	return cmark_render(root, options, width, outc, S_render_node);
 }
diff --git a/src/latex.c b/src/latex.c
index 6eaabce..c3d39da 100644
--- a/src/latex.c
+++ b/src/latex.c
@@ -10,275 +10,174 @@
 #include "buffer.h"
 #include "utf8.h"
 #include "scanners.h"
+#include "render.h"
 
-// Functions to convert cmark_nodes to commonmark strings.
-
-struct render_state {
-	int options;
-	cmark_strbuf* buffer;
-	cmark_strbuf* prefix;
-	int column;
-	int width;
-	int need_cr;
-	int enumlevel;
-	bufsize_t last_breakable;
-	bool begin_line;
-	bool no_wrap;
-	bool in_tight_list_item;
-	bool silence;
-};
-
-static inline void cr(struct render_state *state)
+static inline void outc(cmark_render_state *state,
+			cmark_escaping escape,
+			int32_t c,
+			unsigned char nextc)
 {
-	if (state->need_cr < 1) {
-		state->need_cr = 1;
-	}
-}
-
-static inline void blankline(struct render_state *state)
-{
-	if (state->need_cr < 2) {
-		state->need_cr = 2;
-	}
-}
-
-typedef enum  {
-	LITERAL,
-	NORMAL,
-	URL
-} escaping;
-
-static inline void out(struct render_state *state,
-                       cmark_chunk str,
-                       bool wrap,
-                       escaping escape)
-{
-	unsigned char* source = str.data;
-	int length = str.len;
-	unsigned char nextc;
-	int32_t c;
-	int i = 0;
-	int len;
-	cmark_chunk remainder = cmark_chunk_literal("");
-	int k = state->buffer->size - 1;
-
-	if (state->silence)
-		return;
-
-	wrap = wrap && !state->no_wrap;
-
-	if (state->in_tight_list_item && state->need_cr > 1) {
-		state->need_cr = 1;
-	}
-	while (state->need_cr) {
-		if (k < 0 || state->buffer->ptr[k] == '\n') {
-			k -= 1;
-		} else {
-			cmark_strbuf_putc(state->buffer, '\n');
-			if (state->need_cr > 1) {
-				cmark_strbuf_put(state->buffer, state->prefix->ptr,
-				                 state->prefix->size);
-			}
-		}
-		state->column = 0;
-		state->begin_line = true;
-		state->need_cr -= 1;
-	}
-
-	while (i < length) {
-		if (state->begin_line) {
-			cmark_strbuf_put(state->buffer, state->prefix->ptr,
-			                 state->prefix->size);
-			// note: this assumes prefix is ascii:
-			state->column = state->prefix->size;
-		}
-
-		len = utf8proc_iterate(source + i, length - i, &c);
-		if (len == -1) { // error condition
-			return;  // return without rendering rest of string
-		}
-		nextc = source[i + len];
-		if (c == 32 && wrap) {
-			if (!state->begin_line) {
-				cmark_strbuf_putc(state->buffer, ' ');
+	if (escape == LITERAL) {
+		utf8proc_encode_char(c, state->buffer);
+		state->column += 1;
+	} else {
+		switch(c) {
+		case 123: // '{'
+		case 125: // '}'
+		case 35: // '#'
+		case 37: // '%'
+		case 38: // '&'
+			cmark_strbuf_putc(state->buffer, '\\');
+			utf8proc_encode_char(c, state->buffer);
+			state->column += 2;
+			break;
+		case 36: // '$'
+		case 95: // '_'
+			if (escape == NORMAL) {
+				cmark_strbuf_putc(state->buffer, '\\');
 				state->column += 1;
-				state->begin_line = false;
-				state->last_breakable = state->buffer->size -
-				                        1;
-				// skip following spaces
-				while (source[i + 1] == ' ') {
-					i++;
-				}
 			}
-
-		} else if (c == 10) {
-			cmark_strbuf_putc(state->buffer, '\n');
-			state->column = 0;
-			state->begin_line = true;
-			state->last_breakable = 0;
-		} else if (escape == LITERAL) {
 			utf8proc_encode_char(c, state->buffer);
-			state->column += 2;
-		} else {
-			switch(c) {
-			case 123: // '{'
-			case 125: // '}'
-			case 35: // '#'
-			case 37: // '%'
-			case 38: // '&'
+			state->column += 1;
+			break;
+		case 45 : // '-'
+			if (nextc == 45) { // prevent ligature
 				cmark_strbuf_putc(state->buffer, '\\');
+				state->column += 1;
+			}
+			utf8proc_encode_char(c, state->buffer);
+			state->column += 1;
+			break;
+		case 126: // '~'
+			if (escape == NORMAL) {
+				cmark_strbuf_puts(state->buffer,
+						  "\\textasciitilde{}");
+				state->column += 17;
+			} else {
 				utf8proc_encode_char(c, state->buffer);
+				state->column += 1;
+			}
+			break;
+		case 94: // '^'
+			cmark_strbuf_puts(state->buffer,
+					  "\\^{}");
+			state->column += 4;
+			break;
+		case 92: // '\\'
+			if (escape == URL) {
+				// / acts as path sep even on windows:
+				cmark_strbuf_puts(state->buffer, "/");
+				state->column += 1;
+			} else {
+				cmark_strbuf_puts(state->buffer,
+						  "\\textbackslash{}");
+				state->column += 16;
+			}
+			break;
+		case 124: // '|'
+			cmark_strbuf_puts(state->buffer,
+					  "\\textbar{}");
+			state->column += 10;
+			break;
+		case 60: // '<'
+			cmark_strbuf_puts(state->buffer,
+					  "\\textless{}");
+			state->column += 11;
+			break;
+		case 62: // '>'
+			cmark_strbuf_puts(state->buffer,
+					  "\\textgreater{}");
+			state->column += 14;
+			break;
+		case 91: // '['
+		case 93: // ']'
+			cmark_strbuf_putc(state->buffer, '{');
+			utf8proc_encode_char(c, state->buffer);
+			cmark_strbuf_putc(state->buffer, '}');
+			state->column += 3;
+			break;
+		case 34: // '"'
+			cmark_strbuf_puts(state->buffer,
+					  "\\textquotedbl{}");
+			// requires \usepackage[T1]{fontenc}
+			state->column += 15;
+			break;
+		case 39: // '\''
+			cmark_strbuf_puts(state->buffer,
+					  "\\textquotesingle{}");
+			state->column += 18;
+			// requires \usepackage{textcomp}
+			break;
+		case 160: // nbsp
+			cmark_strbuf_putc(state->buffer, '~');
+			state->column += 1;
+			break;
+		case 8230: // hellip
+			cmark_strbuf_puts(state->buffer, "\\ldots{}");
+			state->column += 8;
+			break;
+		case 8216: // lsquo
+			if (escape == NORMAL) {
+				cmark_strbuf_putc(state->buffer, '`');
+				state->column += 1;
+			} else {
+				utf8proc_encode_char(c, state->buffer);
+				state->column += 1;
+			}
+			break;
+		case 8217: // rsquo
+			if (escape == NORMAL) {
+				cmark_strbuf_putc(state->buffer, '\'');
+				state->column += 1;
+			} else {
+				utf8proc_encode_char(c, state->buffer);
+				state->column += 1;
+			}
+			break;
+		case 8220: // ldquo
+			if (escape == NORMAL) {
+				cmark_strbuf_puts(state->buffer, "``");
 				state->column += 2;
-				break;
-			case 36: // '$'
-			case 95: // '_'
-				if (escape == NORMAL) {
-					cmark_strbuf_putc(state->buffer, '\\');
-				}
+			} else {
 				utf8proc_encode_char(c, state->buffer);
-				break;
-			case 45 : // '-'
-				if (nextc == 45) { // prevent ligature
-					cmark_strbuf_putc(state->buffer, '\\');
-				}
+				state->column += 1;
+			}
+			break;
+		case 8221: // rdquo
+			if (escape == NORMAL) {
+				cmark_strbuf_puts(state->buffer, "''");
+				state->column += 2;
+			} else {
 				utf8proc_encode_char(c, state->buffer);
-				break;
-			case 126: // '~'
-				if (escape == NORMAL) {
-					cmark_strbuf_puts(state->buffer,
-					                  "\\textasciitilde{}");
-				} else {
-					utf8proc_encode_char(c, state->buffer);
-				}
-				break;
-			case 94: // '^'
-				cmark_strbuf_puts(state->buffer,
-				                  "\\^{}");
-				break;
-			case 92: // '\\'
-				if (escape == URL) {
-					// / acts as path sep even on windows:
-					cmark_strbuf_puts(state->buffer, "/");
-				} else {
-					cmark_strbuf_puts(state->buffer,
-					                  "\\textbackslash{}");
-				}
-				break;
-			case 124: // '|'
-				cmark_strbuf_puts(state->buffer,
-				                  "\\textbar{}");
-				break;
-			case 60: // '<'
-				cmark_strbuf_puts(state->buffer,
-				                  "\\textless{}");
-				break;
-			case 62: // '>'
-				cmark_strbuf_puts(state->buffer,
-				                  "\\textgreater{}");
-				break;
-			case 91: // '['
-			case 93: // ']'
-				cmark_strbuf_putc(state->buffer, '{');
+				state->column += 1;
+			}
+			break;
+		case 8212: // emdash
+			if (escape == NORMAL) {
+				cmark_strbuf_puts(state->buffer, "---");
+				state->column += 3;
+			} else {
 				utf8proc_encode_char(c, state->buffer);
-				cmark_strbuf_putc(state->buffer, '}');
-				break;
-			case 34: // '"'
-				cmark_strbuf_puts(state->buffer,
-				                  "\\textquotedbl{}");
-				// requires \usepackage[T1]{fontenc}
-				break;
-			case 39: // '\''
-				cmark_strbuf_puts(state->buffer,
-				                  "\\textquotesingle{}");
-				// requires \usepackage{textcomp}
-				break;
-			case 160: // nbsp
-				cmark_strbuf_putc(state->buffer, '~');
-				break;
-			case 8230: // hellip
-				cmark_strbuf_puts(state->buffer, "\\ldots{}");
-				break;
-			case 8216: // lsquo
-				if (escape == NORMAL) {
-					cmark_strbuf_putc(state->buffer, '`');
-				} else {
-					utf8proc_encode_char(c, state->buffer);
-				}
-				break;
-			case 8217: // rsquo
-				if (escape == NORMAL) {
-					cmark_strbuf_putc(state->buffer, '\'');
-				} else {
-					utf8proc_encode_char(c, state->buffer);
-				}
-				break;
-			case 8220: // ldquo
-				if (escape == NORMAL) {
-					cmark_strbuf_puts(state->buffer, "``");
-				} else {
-					utf8proc_encode_char(c, state->buffer);
-				}
-				break;
-			case 8221: // rdquo
-				if (escape == NORMAL) {
-					cmark_strbuf_puts(state->buffer, "''");
-				} else {
-					utf8proc_encode_char(c, state->buffer);
-				}
-				break;
-			case 8212: // emdash
-				if (escape == NORMAL) {
-					cmark_strbuf_puts(state->buffer, "---");
-				} else {
-					utf8proc_encode_char(c, state->buffer);
-				}
-				break;
-			case 8211: // endash
-				if (escape == NORMAL) {
-					cmark_strbuf_puts(state->buffer, "--");
-				} else {
-					utf8proc_encode_char(c, state->buffer);
-				}
-				break;
-			default:
+				state->column += 1;
+			}
+			break;
+		case 8211: // endash
+			if (escape == NORMAL) {
+				cmark_strbuf_puts(state->buffer, "--");
+				state->column += 2;
+			} else {
 				utf8proc_encode_char(c, state->buffer);
 				state->column += 1;
-				state->begin_line = false;
 			}
-		}
-
-		// If adding the character went beyond width, look for an
-		// earlier place where the line could be broken:
-		if (state->width > 0 &&
-		    state->column > state->width &&
-		    !state->begin_line &&
-		    state->last_breakable > 0) {
-
-			// copy from last_breakable to remainder
-			cmark_chunk_set_cstr(&remainder, (char *) state->buffer->ptr + state->last_breakable + 1);
-			// truncate at last_breakable
-			cmark_strbuf_truncate(state->buffer, state->last_breakable);
-			// add newline, prefix, and remainder
-			cmark_strbuf_putc(state->buffer, '\n');
-			cmark_strbuf_put(state->buffer, state->prefix->ptr,
-			                 state->prefix->size);
-			cmark_strbuf_put(state->buffer, remainder.data, remainder.len);
-			state->column = state->prefix->size + remainder.len;
-			cmark_chunk_free(&remainder);
-			state->last_breakable = 0;
+			break;
+		default:
+			utf8proc_encode_char(c, state->buffer);
+			state->column += 1;
 			state->begin_line = false;
 		}
-
-		i += len;
 	}
 }
 
-static void lit(struct render_state *state, char *s, bool wrap)
-{
-	cmark_chunk str = cmark_chunk_literal(s);
-	out(state, str, wrap, LITERAL);
-}
-
 typedef enum  {
 	NO_LINK,
 	URL_AUTOLINK,
@@ -349,7 +248,7 @@ get_containing_block(cmark_node *node)
 
 static int
 S_render_node(cmark_node *node, cmark_event_type ev_type,
-              struct render_state *state)
+              cmark_render_state *state)
 {
 	cmark_node *tmp;
 	int list_number;
@@ -568,9 +467,7 @@ S_render_node(cmark_node *node, cmark_event_type ev_type,
 			// requires \include{graphicx}
 			out(state, url, false, URL);
 			lit(state, "}", false);
-			state->silence = true; // don't print the alt text
-		} else {
-			state->silence = false;
+			return 0;
 		}
 		break;
 
@@ -584,32 +481,5 @@ S_render_node(cmark_node *node, cmark_event_type ev_type,
 
 char *cmark_render_latex(cmark_node *root, int options, int width)
 {
-	char *result;
-	cmark_strbuf commonmark = GH_BUF_INIT;
-	cmark_strbuf prefix = GH_BUF_INIT;
-	if (CMARK_OPT_HARDBREAKS & options) {
-		width = 0;
-	}
-	struct render_state state = {
-		options, &commonmark, &prefix, 0, width,
-		0, 0, 0, true, false, false, false
-	};
-	cmark_node *cur;
-	cmark_event_type ev_type;
-	cmark_iter *iter = cmark_iter_new(root);
-
-	while ((ev_type = cmark_iter_next(iter)) != CMARK_EVENT_DONE) {
-		cur = cmark_iter_get_node(iter);
-		if (!S_render_node(cur, ev_type, &state)) {
-			// a false value causes us to skip processing
-			// the node's contents.  this is used for
-			// autolinks.
-			cmark_iter_reset(iter, cur, CMARK_EVENT_EXIT);
-		}
-	}
-	result = (char *)cmark_strbuf_detach(&commonmark);
-
-	cmark_strbuf_free(&prefix);
-	cmark_iter_free(iter);
-	return result;
+	return cmark_render(root, options, width, outc, S_render_node);
 }
diff --git a/src/render.c b/src/render.c
new file mode 100644
index 0000000..0fec3c4
--- /dev/null
+++ b/src/render.c
@@ -0,0 +1,186 @@
+#include <stdlib.h>
+#include "buffer.h"
+#include "chunk.h"
+#include "cmark.h"
+#include "utf8.h"
+#include "render.h"
+
+static inline
+cmark_render_state
+cmark_initialize_render_state(int options, int width,
+			      void (*outc)(cmark_render_state*,
+				           cmark_escaping,
+					   int32_t,
+					   unsigned char))
+{
+	cmark_strbuf *pref = (cmark_strbuf*)malloc(sizeof(cmark_strbuf));
+	cmark_strbuf *buf  = (cmark_strbuf*)malloc(sizeof(cmark_strbuf));
+	cmark_strbuf_init(pref, 16);
+	cmark_strbuf_init(buf, 1024);
+	cmark_render_state state = { options, buf, pref, 0, width,
+				     0, 0, 0, true, false, false, outc };
+	return state;
+}
+
+static inline
+char *
+cmark_finalize_render_state(cmark_render_state *state)
+{
+	char * result;
+	result = (char *)cmark_strbuf_detach(state->buffer);
+	cmark_strbuf_free(state->prefix);
+	cmark_strbuf_free(state->buffer);
+	free(state->prefix);
+	free(state->buffer);
+	return result;
+}
+
+void cr(cmark_render_state *state)
+{
+	if (state->need_cr < 1) {
+		state->need_cr = 1;
+	}
+}
+
+void blankline(cmark_render_state *state)
+{
+	if (state->need_cr < 2) {
+		state->need_cr = 2;
+	}
+}
+
+void out(cmark_render_state *state,
+	 cmark_chunk str,
+	 bool wrap,
+	 cmark_escaping escape)
+{
+	unsigned char* source = str.data;
+	int length = str.len;
+	unsigned char nextc;
+	int32_t c;
+	int i = 0;
+	int len;
+	cmark_chunk remainder = cmark_chunk_literal("");
+	int k = state->buffer->size - 1;
+
+	wrap = wrap && !state->no_wrap;
+
+	if (state->in_tight_list_item && state->need_cr > 1) {
+		state->need_cr = 1;
+	}
+	while (state->need_cr) {
+		if (k < 0 || state->buffer->ptr[k] == '\n') {
+			k -= 1;
+		} else {
+			cmark_strbuf_putc(state->buffer, '\n');
+			if (state->need_cr > 1) {
+				cmark_strbuf_put(state->buffer, state->prefix->ptr,
+				                 state->prefix->size);
+			}
+		}
+		state->column = 0;
+		state->begin_line = true;
+		state->need_cr -= 1;
+	}
+
+	while (i < length) {
+		if (state->begin_line) {
+			cmark_strbuf_put(state->buffer, state->prefix->ptr,
+			                 state->prefix->size);
+			// note: this assumes prefix is ascii:
+			state->column = state->prefix->size;
+		}
+
+		len = utf8proc_iterate(source + i, length - i, &c);
+		if (len == -1) { // error condition
+			return;  // return without rendering rest of string
+		}
+		nextc = source[i + len];
+		if (c == 32 && wrap) {
+			if (!state->begin_line) {
+				cmark_strbuf_putc(state->buffer, ' ');
+				state->column += 1;
+				state->begin_line = false;
+				state->last_breakable = state->buffer->size -
+				                        1;
+				// skip following spaces
+				while (source[i + 1] == ' ') {
+					i++;
+				}
+			}
+
+		} else if (c == 10) {
+			cmark_strbuf_putc(state->buffer, '\n');
+			state->column = 0;
+			state->begin_line = true;
+			state->last_breakable = 0;
+		} else {
+			(state->outc)(state, escape, c, nextc);
+		}
+
+		// If adding the character went beyond width, look for an
+		// earlier place where the line could be broken:
+		if (state->width > 0 &&
+		    state->column > state->width &&
+		    !state->begin_line &&
+		    state->last_breakable > 0) {
+
+			// copy from last_breakable to remainder
+			cmark_chunk_set_cstr(&remainder, (char *) state->buffer->ptr + state->last_breakable + 1);
+			// truncate at last_breakable
+			cmark_strbuf_truncate(state->buffer, state->last_breakable);
+			// add newline, prefix, and remainder
+			cmark_strbuf_putc(state->buffer, '\n');
+			cmark_strbuf_put(state->buffer, state->prefix->ptr,
+			                 state->prefix->size);
+			cmark_strbuf_put(state->buffer, remainder.data, remainder.len);
+			state->column = state->prefix->size + remainder.len;
+			cmark_chunk_free(&remainder);
+			state->last_breakable = 0;
+			state->begin_line = false;
+		}
+
+		i += len;
+	}
+}
+
+void lit(cmark_render_state *state, char *s, bool wrap)
+{
+	cmark_chunk str = cmark_chunk_literal(s);
+	out(state, str, wrap, LITERAL);
+}
+
+char*
+cmark_render(cmark_node *root,
+	     int options,
+	     int width,
+	     void (*outc)(cmark_render_state*,
+			  cmark_escaping,
+			  int32_t,
+			  unsigned char),
+	     int (*render_node)(cmark_node *node,
+				 cmark_event_type ev_type,
+				 cmark_render_state *state))
+{
+	if (CMARK_OPT_HARDBREAKS & options) {
+		width = 0;
+	}
+	cmark_render_state state = cmark_initialize_render_state(options, width, outc);
+	cmark_node *cur;
+	cmark_event_type ev_type;
+	cmark_iter *iter = cmark_iter_new(root);
+
+	while ((ev_type = cmark_iter_next(iter)) != CMARK_EVENT_DONE) {
+		cur = cmark_iter_get_node(iter);
+		if (!render_node(cur, ev_type, &state)) {
+			// a false value causes us to skip processing
+			// the node's contents.  this is used for
+			// autolinks.
+			cmark_iter_reset(iter, cur, CMARK_EVENT_EXIT);
+		}
+	}
+
+	cmark_iter_free(iter);
+
+	return cmark_finalize_render_state(&state);
+}
diff --git a/src/render.h b/src/render.h
new file mode 100644
index 0000000..6c268a1
--- /dev/null
+++ b/src/render.h
@@ -0,0 +1,67 @@
+#ifndef CMARK_RENDER_H
+#define CMARK_RENDER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdlib.h>
+#include "buffer.h"
+#include "chunk.h"
+
+typedef enum  {
+	LITERAL,
+	NORMAL,
+	TITLE,
+	URL
+} cmark_escaping;
+
+struct cmark_render_state {
+	int options;
+	cmark_strbuf* buffer;
+	cmark_strbuf* prefix;
+	int column;
+	int width;
+	int need_cr;
+	bufsize_t last_breakable;
+	int enumlevel;
+	bool begin_line;
+	bool no_wrap;
+	bool in_tight_list_item;
+	void (*outc)(struct cmark_render_state*,
+		     cmark_escaping,
+		     int32_t,
+		     unsigned char);
+};
+
+typedef struct cmark_render_state cmark_render_state;
+
+void cr(cmark_render_state *state);
+
+void blankline(cmark_render_state *state);
+
+void out(cmark_render_state *state,
+	 cmark_chunk str,
+	 bool wrap,
+	 cmark_escaping escape);
+
+void lit(cmark_render_state *state, char *s, bool wrap);
+
+char*
+cmark_render(cmark_node *root,
+	     int options,
+	     int width,
+	     void (*outc)(cmark_render_state*,
+			  cmark_escaping,
+			  int32_t,
+			  unsigned char),
+	     int (*render_node)(cmark_node *node,
+				cmark_event_type ev_type,
+				cmark_render_state *state));
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
-- 
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