From 6939753ca04416082720a0e773a3491686f25a4d Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <mike.gerwitz@ryansg.com>
Date: Mon, 13 Jan 2020 16:41:06 -0500
Subject: [PATCH] TAMER: POC: Output xmle

This is a working proof-of-concept that will be finalized in future commits.
---
 .rev-xmle                       |   2 +-
 build-aux/Makefile.am           |   3 +-
 src/current/compiler/js.xsl     |  32 ++--
 src/current/compiler/linker.xsl |  29 ---
 src/current/standalone.xsl      |  22 ++-
 tamer/src/ir/asg/object.rs      |  17 ++
 tamer/src/ir/legacyir.rs        |  28 +++
 tamer/src/ld/poc.rs             | 310 ++++++++++++++++++++++++++++++--
 tamer/src/obj/xmlo/reader.rs    | 233 +++++++++++++++++++++++-
 9 files changed, 595 insertions(+), 81 deletions(-)

diff --git a/.rev-xmle b/.rev-xmle
index d895b0af..791ebc98 100644
--- a/.rev-xmle
+++ b/.rev-xmle
@@ -1,4 +1,4 @@
 # This number is incremented for every linker change to force rebuilding
 # of xmle files.
-0
+1
 
diff --git a/build-aux/Makefile.am b/build-aux/Makefile.am
index 9c955715..e8ab2664 100644
--- a/build-aux/Makefile.am
+++ b/build-aux/Makefile.am
@@ -132,7 +132,8 @@ standalones: $(dest_standalone)
 strip: $(dest_standalone_strip) ui/package.strip.js
 %.xmle: %.xmlo $(path_tame)/.rev-xmle
 	$(TAME_TS)
-	$(TAME) link $< $@
+	@echo "WARNING: using WIP proof-of-concept linker!"
+	set -o pipefail; $(path_tame)/tamer/target/release/tameld $< | awk '/^<package/{p=1};p' > $@
 %.js: %.xmle
 	$(TAME_TS)
 	$(TAME) standalone $< $@
diff --git a/src/current/compiler/js.xsl b/src/current/compiler/js.xsl
index cba86787..a756db1a 100644
--- a/src/current/compiler/js.xsl
+++ b/src/current/compiler/js.xsl
@@ -62,7 +62,7 @@
 
   @return compiled JS
 -->
-<template match="lv:package" mode="compiler:entry">
+<template name="compiler:entry">
   <!-- enclose everything in a self-executing function to sandbox our data -->
   <text>( function() { </text>
     <!-- to store debug information for equations (we have to put this out here
@@ -76,7 +76,7 @@
 </template>
 
 
-<template match="lv:package" mode="compiler:entry-rater">
+<template name="compiler:entry-rater">
     <!-- the rater itself -->
     <value-of select="$compiler:nl" />
     <text>function rater( arglist, _canterm ) {</text>
@@ -107,16 +107,13 @@
       <text>/**@expose*/var genclasses = {};</text>
 </template>
 
-<template match="lv:package" mode="compiler:entry-classifier">
+<template name="compiler:classifier">
   <!-- allow classification of any arbitrary dataset -->
   <value-of select="$compiler:nl" />
   <text>rater.classify = function( args, _canterm ) {</text>
     return rater( args, _canterm ).classes;
   <text> };</text>
-</template>
 
-<template match="lv:package" mode="compiler:exit-classifier">
-  <!-- TODO: make sure fromMap has actually been compiled -->
   <text>rater.classify.fromMap = function( args_base, _canterm ) { </text>
     <text>var ret = {}; </text>
     <text>rater.fromMap( args_base, function( args ) {</text>
@@ -136,8 +133,10 @@
   <text> }; </text>
 </template>
 
-<template match="lv:package" mode="compiler:exit-rater">
+<template name="compiler:exit-rater">
+  <param name="name" as="xs:string "/>
   <param name="symbols" as="element( preproc:sym )*" />
+  <param name="mapfrom" as="element()*" />
 
       <value-of select="$compiler:nl" />
       <text>return { </text>
@@ -152,7 +151,7 @@
 
     <!-- make the name of the supplier available -->
     <text>/**@expose*/rater.supplier = '</text>
-      <value-of select="substring-after( @name, '/' )" />
+      <value-of select="substring-after( $name, '/' )" />
     <text>'; </text>
 
     <text>/**@expose*/rater.meta = meta;</text>
@@ -174,20 +173,8 @@
           $symbols[ @type='class' ] )" />
     <text> }; </text>
 
-    <variable name="mapfrom" select="
-        preproc:symtable/preproc:sym[
-          @type='map'
-        ]/preproc:from[
-          not(
-            @name = parent::preproc:sym
-              /preceding-sibling::preproc:sym[
-                @type='map'
-              ]/preproc:from/@name
-          )
-        ]
-      " />
-
     <!-- mapped fields (external names) -->
+    <value-of select="$compiler:nl" />
     <text>/**@expose*/rater.knownFields = {</text>
       <for-each select="$mapfrom">
         <if test="position() > 1">
@@ -221,6 +208,7 @@
     <text>'</text>
       <value-of select="substring-after( @name, ':class:' )" />
     <text>':'</text>
+      <!-- yields -->
       <value-of select="@yields" />
     <text>'</text>
   </for-each>
@@ -239,7 +227,7 @@
       <value-of select="substring-after( @name, ':class:' )" />
     <text>':'</text>
       <!-- todo: escape -->
-      <value-of select="translate( @desc, &quot;'&quot;, '' )" />
+      <value-of select="translate( normalize-space(@desc), &quot;'&quot;, '' )" />
     <text>'</text>
   </for-each>
 </function>
diff --git a/src/current/compiler/linker.xsl b/src/current/compiler/linker.xsl
index b1f6c3fe..3fb96c4a 100644
--- a/src/current/compiler/linker.xsl
+++ b/src/current/compiler/linker.xsl
@@ -799,8 +799,6 @@
     </with-param>
   </call-template>
 
-  <apply-templates select="." mode="compiler:entry" />
-
 
   <apply-templates select="." mode="l:link-meta">
     <with-param name="deps" select="$deps" />
@@ -808,9 +806,6 @@
   <apply-templates select="." mode="l:link-worksheet">
     <with-param name="deps" select="$deps" />
   </apply-templates>
-  <apply-templates select="." mode="l:link-classifier">
-    <with-param name="deps" select="$deps" />
-  </apply-templates>
   <apply-templates select="." mode="l:link-params">
     <with-param name="deps" select="$deps" />
   </apply-templates>
@@ -824,9 +819,6 @@
     <with-param name="deps" select="$deps" />
   </apply-templates>
 
-  <!-- common stuff -->
-  <call-template name="compiler:static" />
-
   <!-- finally, finish up -->
   <call-template name="log:info">
     <with-param name="name" select="'link'" />
@@ -908,21 +900,6 @@
 </template>
 
 
-<template match="lv:package" mode="l:link-classifier">
-  <call-template name="log:info">
-    <with-param name="name" select="'link'" />
-    <with-param name="msg">
-      <text>** linking classifier...</text>
-    </with-param>
-  </call-template>
-
-  <!-- link everything that shall be a part of the classifier -->
-  <apply-templates select="." mode="compiler:entry-classifier" />
-  <!-- TODO: get rid of me completely! -->
-  <apply-templates select="." mode="compiler:exit-classifier" />
-</template>
-
-
 <template match="lv:package" mode="l:link-params">
   <param name="deps" />
 
@@ -990,8 +967,6 @@
     </with-param>
   </call-template>
 
-  <apply-templates select="." mode="compiler:entry-rater" />
-
   <!-- TODO: this list of exclusions is a mess -->
   <apply-templates select="." mode="l:do-link">
     <with-param name="symbols" select="
@@ -1008,10 +983,6 @@
   <sequence select="l:link-exit-fragments(
                           $rater-exit-fragments,
                           . )" />
-
-  <apply-templates select="." mode="compiler:exit-rater">
-    <with-param name="symbols" select="$deps" />
-  </apply-templates>
 </template>
 
 
diff --git a/src/current/standalone.xsl b/src/current/standalone.xsl
index 809a7656..59b29faa 100644
--- a/src/current/standalone.xsl
+++ b/src/current/standalone.xsl
@@ -36,10 +36,7 @@
             xmlns:preproc="http://www.lovullo.com/rater/preproc">
 
 
-<output
-  indent="yes"
-  omit-xml-declaration="yes"
-  />
+<output method="text" />
 
 <include href="include/dslc-base.xsl" />
 
@@ -54,9 +51,22 @@
 <template match="/" priority="5">
   <!-- the rater itself -->
   <text>var rater = </text>
+    <!-- (moved from linker during TAMER POC linker) -->
+    <call-template name="compiler:entry" />
+    <call-template name="compiler:classifier" />
+    <call-template name="compiler:entry-rater" />
+
     <value-of disable-output-escaping="yes" select="/lv:package/l:exec/text()" />
   <text>; </text>
 
+  <!--(moved from linker during TAMER POC linker) -->
+  <call-template name="compiler:exit-rater">
+    <with-param name="name" select="/*/@name" />
+    <with-param name="symbols" select="/*/l:dep/preproc:sym" />
+    <with-param name="mapfrom" select="/*/l:map-from/l:from" />
+  </call-template>
+  <call-template name="compiler:static" />
+
   <!-- maps may or may not exist -->
   <variable name="map" select="/lv:package/l:map-exec" />
   <variable name="retmap" select="/lv:package/l:retmap-exec" />
@@ -64,7 +74,7 @@
   <!-- store a reference to the mapper in rater.fromMap() -->
   <text>rater.fromMap = </text>
     <choose>
-      <when test="$map">
+      <when test="/lv:package/l:dep/preproc:sym[@type='map'][1]">
         <value-of disable-output-escaping="yes" select="$map/text()" />
       </when>
 
@@ -79,7 +89,7 @@
   <!-- return map -->
   <text>rater._retmap = </text>
     <choose>
-      <when test="$retmap">
+      <when test="/lv:package/l:dep/preproc:sym[@type='retmap'][1]">
         <value-of disable-output-escaping="yes" select="$retmap/text()" />
       </when>
 
diff --git a/tamer/src/ir/asg/object.rs b/tamer/src/ir/asg/object.rs
index 1e3019aa..1c370503 100644
--- a/tamer/src/ir/asg/object.rs
+++ b/tamer/src/ir/asg/object.rs
@@ -113,6 +113,19 @@ pub struct Source<'i> {
     ///
     /// Identifiers created by templates are not considered to be generated.
     pub generated: bool,
+
+    /// Related identifiers.
+    ///
+    /// These data represent a kluge created to add additional symbol
+    /// information in two different contexts:
+    ///
+    ///  - [`IdentKind::Map`] includes the name of the source field; and
+    ///  - [`IdentKind::Func`] lists params in order (so that the compiler
+    ///    knows application order).
+    ///
+    /// TODO: We have `parent`, `yields`, and `from`.
+    ///   We should begin to consolodate.
+    pub from: Option<Vec<&'i Symbol<'i>>>,
 }
 
 impl<'i> From<SymAttrs<'i>> for Source<'i> {
@@ -125,6 +138,7 @@ impl<'i> From<SymAttrs<'i>> for Source<'i> {
             parent: attrs.parent,
             yields: attrs.yields,
             desc: attrs.desc,
+            from: attrs.from,
         }
     }
 }
@@ -138,12 +152,14 @@ mod test {
     fn source_from_sym_attrs() {
         let psym = Symbol::new_dummy(SymbolIndex::from_u32(1), "parent");
         let ysym = Symbol::new_dummy(SymbolIndex::from_u32(2), "yields");
+        let fsym = Symbol::new_dummy(SymbolIndex::from_u32(2), "from");
 
         let attrs = SymAttrs {
             generated: true,
             parent: Some(&psym),
             yields: Some(&ysym),
             desc: Some("sym desc".to_string()),
+            from: Some(vec![&fsym]),
             ..Default::default()
         };
 
@@ -153,6 +169,7 @@ mod test {
                 parent: attrs.parent,
                 yields: attrs.yields,
                 desc: Some("sym desc".to_string()),
+                from: Some(vec![&fsym]),
             },
             attrs.into(),
         );
diff --git a/tamer/src/ir/legacyir.rs b/tamer/src/ir/legacyir.rs
index 5d88af9b..b0d2e7ee 100644
--- a/tamer/src/ir/legacyir.rs
+++ b/tamer/src/ir/legacyir.rs
@@ -131,6 +131,16 @@ pub struct SymAttrs<'i> {
     ///
     /// This is used primarily by [`SymType::Class`] and [`SymType::Gen`].
     pub desc: Option<String>,
+
+    /// Related identifiers.
+    ///
+    /// These data represent a kluge created to add additional symbol
+    /// information in two different contexts:
+    ///
+    ///  - [`SymType::Map`] includes the name of the source field; and
+    ///  - [`SymType::Func`] lists params in order (so that the compiler
+    ///    knows application order).
+    pub from: Option<Vec<&'i Symbol<'i>>>,
 }
 
 /// Legacy symbol types.
@@ -232,6 +242,18 @@ pub enum SymDtype {
     Empty,
 }
 
+impl AsRef<str> for SymDtype {
+    /// Produce `xmlo`-compatible representation.
+    fn as_ref(&self) -> &str {
+        match self {
+            SymDtype::Boolean => &"boolean",
+            SymDtype::Integer => &"integer",
+            SymDtype::Float => &"float",
+            SymDtype::Empty => &"empty",
+        }
+    }
+}
+
 impl TryFrom<&[u8]> for SymDtype {
     type Error = String;
 
@@ -289,4 +311,10 @@ mod test {
             bad => panic!("expected error: {:?}", bad),
         }
     }
+
+    #[test]
+    fn symdtype_as_str() {
+        let boolean: &str = SymDtype::Boolean.as_ref();
+        assert_eq!("boolean", boolean);
+    }
 }
diff --git a/tamer/src/ld/poc.rs b/tamer/src/ld/poc.rs
index d11d8637..59928f3f 100644
--- a/tamer/src/ld/poc.rs
+++ b/tamer/src/ld/poc.rs
@@ -24,11 +24,13 @@ use crate::ir::asg::{Asg, DefaultAsg, Object, ObjectRef};
 use crate::obj::xmlo::reader::{XmloError, XmloEvent, XmloReader};
 use crate::sym::{DefaultInterner, Interner};
 use petgraph::visit::DfsPostOrder;
+use quick_xml::events::{BytesEnd, BytesStart, BytesText, Event};
+use quick_xml::Writer;
 use std::collections::{HashMap, HashSet};
 use std::convert::TryInto;
 use std::error::Error;
 use std::fs;
-use std::io::BufReader;
+use std::io::{BufReader, Write};
 
 type LinkerAsg<'i> = DefaultAsg<'i, global::ProgIdentSize>;
 type LinkerObjectRef = ObjectRef<global::ProgIdentSize>;
@@ -73,7 +75,9 @@ pub fn main() -> Result<(), Box<dyn Error>> {
 
     let sorted = sort_deps(&depgraph, &roots);
 
-    println!("Sorted ({}): {:?}", sorted.len(), sorted);
+    //println!("Sorted ({}): {:?}", sorted.len(), sorted);
+
+    output_xmle(&depgraph, &interner, sorted)?;
 
     Ok(())
 }
@@ -118,13 +122,18 @@ fn load_xmlo<'a, 'i, I: Interner<'i>>(
                     .lookup(sym)
                     .expect(&format!("missing sym for deps: `{}`", sym));
 
-                for dep_sym in deps {
-                    let dep_node = depgraph.lookup(dep_sym).expect(&format!(
-                        "missing dep sym for deps: `{}` -> `{}`",
-                        sym, dep_sym
-                    ));
+                // Maps should not pull in symbols since we may end up
+                // mapping to params that are never actually used
+                if !sym.starts_with(":map:") {
+                    for dep_sym in deps {
+                        let dep_node =
+                            depgraph.lookup(dep_sym).expect(&format!(
+                                "missing dep sym for deps: `{}` -> `{}`",
+                                sym, dep_sym
+                            ));
 
-                    depgraph.add_dep(sym_node, dep_node);
+                        depgraph.add_dep(sym_node, dep_node);
+                    }
                 }
             }
 
@@ -147,8 +156,8 @@ fn load_xmlo<'a, 'i, I: Interner<'i>>(
                         // TODO: inefficient
                         let link_root = owned
                             && (kindval == IdentKind::Meta
-                                || sym.starts_with(":map:")
-                                || sym.starts_with(":retmap:"));
+                                || kindval == IdentKind::Map
+                                || kindval == IdentKind::RetMap);
 
                         let node = depgraph.declare(sym, kindval, src)?;
 
@@ -211,18 +220,35 @@ fn load_xmlo<'a, 'i, I: Interner<'i>>(
     Ok(())
 }
 
+type ObjectVec<'a, 'i> = Vec<&'a Object<'i>>;
+
+// Note that the classifier has nothing in it anymore; it's only there for
+// API compability, so we don't include it here.
+#[derive(Default)]
+struct SortedDeps<'a, 'i> {
+    map: ObjectVec<'a, 'i>,
+    retmap: ObjectVec<'a, 'i>,
+    meta: ObjectVec<'a, 'i>,
+    worksheet: ObjectVec<'a, 'i>,
+    params: ObjectVec<'a, 'i>,
+    types: ObjectVec<'a, 'i>,
+    funcs: ObjectVec<'a, 'i>,
+    rater: ObjectVec<'a, 'i>,
+}
+
 fn sort_deps<'a, 'i>(
     depgraph: &'a LinkerAsg<'i>,
     roots: &Vec<LinkerObjectRef>,
-) -> Vec<&'a Object<'i>> {
+) -> SortedDeps<'a, 'i> {
     // @type=meta, @preproc:elig-class-yields
     // @type={ret}map{,:head,:tail}
 
+    let mut deps: SortedDeps = Default::default();
+
     // This is technically a topological sort, but functions have
     // cycles.  Once we have more symbol metadata, we can filter them out
     // and actually invoke toposort.
     let mut dfs = DfsPostOrder::empty(&depgraph);
-    let mut sorted = Vec::new();
 
     //println!("discovered roots: {:?}", roots);
 
@@ -233,10 +259,266 @@ fn sort_deps<'a, 'i>(
 
     // TODO: can we encapsulate NodeIndex?
     while let Some(index) = dfs.next(&depgraph) {
-        sorted.push(depgraph.get(index).unwrap());
+        let ident = depgraph.get(index).unwrap();
+
+        match ident {
+            Object::Ident(_, kind, _)
+            | Object::IdentFragment(_, kind, _, _) => match kind {
+                IdentKind::Meta => deps.meta.push(ident),
+                IdentKind::Worksheet => deps.worksheet.push(ident),
+                IdentKind::Param(_, _) => deps.params.push(ident),
+                IdentKind::Type(_) => deps.types.push(ident),
+                IdentKind::Func(_, _) => deps.funcs.push(ident),
+                IdentKind::MapHead | IdentKind::Map | IdentKind::MapTail => {
+                    deps.map.push(ident)
+                }
+                IdentKind::RetMapHead
+                | IdentKind::RetMap
+                | IdentKind::RetMapTail => deps.retmap.push(ident),
+                _ => deps.rater.push(ident),
+            },
+            _ => panic!("unexpected node: {:?}", ident),
+        }
     }
 
-    sorted
+    deps
+}
+
+fn output_xmle<'a, 'i, I: Interner<'i>>(
+    depgraph: &'a LinkerAsg<'i>,
+    interner: &'i I,
+    sorted: SortedDeps<'a, 'i>,
+) -> Result<(), Box<dyn Error>> {
+    use std::io::Cursor;
+
+    let mut writer =
+        Writer::new_with_indent(Cursor::new(Vec::new()), ' ' as u8, 2);
+
+    let root =
+        BytesStart::owned_name(b"package".to_vec()).with_attributes(vec![
+            ("xmlns", "http://www.lovullo.com/rater"),
+            ("xmlns:preproc", "http://www.lovullo.com/rater/preproc"),
+            ("xmlns:l", "http://www.lovullo.com/rater/linker"),
+            ("title", "Title TODO"), // TODO
+            ("program", "true"),
+            ("name", "name/todo"), // TODO
+        ]);
+
+    writer.write_event(Event::Start(root))?;
+
+    // All of the other namespaces output in the existing xmle files are
+    // unneeded.
+    writer.write_event(Event::Start(BytesStart::borrowed_name(b"l:dep")))?;
+
+    let all = sorted
+        .meta
+        .iter()
+        .chain(sorted.map.iter())
+        .chain(sorted.retmap.iter())
+        .chain(sorted.worksheet.iter())
+        .chain(sorted.params.iter())
+        .chain(sorted.types.iter())
+        .chain(sorted.funcs.iter())
+        .chain(sorted.rater.iter());
+
+    for ident in all {
+        // TODO: we're doing this in two places!
+        match ident {
+            Object::Ident(sym, kind, src)
+            | Object::IdentFragment(sym, kind, src, _) => {
+                let name: &str = sym;
+
+                // this'll be formalized more sanely
+                let mut attrs = match kind {
+                    IdentKind::Cgen(dim) => {
+                        vec![("type", "cgen"), ("dim", dim.as_ref())]
+                    }
+                    IdentKind::Class(dim) => {
+                        vec![("type", "class"), ("dim", dim.as_ref())]
+                    }
+                    IdentKind::Const(dim, dtype) => vec![
+                        ("type", "const"),
+                        ("dim", dim.as_ref()),
+                        ("dtype", dtype.as_ref()),
+                    ],
+                    IdentKind::Func(dim, dtype) => vec![
+                        ("type", "func"),
+                        ("dim", dim.as_ref()),
+                        ("dtype", dtype.as_ref()),
+                    ],
+                    IdentKind::Gen(dim, dtype) => vec![
+                        ("type", "gen"),
+                        ("dim", dim.as_ref()),
+                        ("dtype", dtype.as_ref()),
+                    ],
+                    IdentKind::Lparam(dim, dtype) => vec![
+                        ("type", "lparam"),
+                        ("dim", dim.as_ref()),
+                        ("dtype", dtype.as_ref()),
+                    ],
+                    IdentKind::Param(dim, dtype) => vec![
+                        ("type", "param"),
+                        ("dim", dim.as_ref()),
+                        ("dtype", dtype.as_ref()),
+                    ],
+                    IdentKind::Rate(dtype) => {
+                        vec![("type", "rate"), ("dtype", dtype.as_ref())]
+                    }
+                    IdentKind::Tpl => vec![("type", "tpl")],
+                    IdentKind::Type(dtype) => {
+                        vec![("type", "type"), ("dtype", dtype.as_ref())]
+                    }
+                    IdentKind::MapHead => vec![("type", "map:head")],
+                    IdentKind::Map => vec![("type", "map")],
+                    IdentKind::MapTail => vec![("type", "map:tail")],
+                    IdentKind::RetMapHead => vec![("type", "retmap:head")],
+                    IdentKind::RetMap => vec![("type", "retmap")],
+                    IdentKind::RetMapTail => vec![("type", "retmap:tail")],
+                    IdentKind::Meta => vec![("type", "meta")],
+                    IdentKind::Worksheet => vec![("type", "worksheet")],
+                };
+
+                attrs.push(("name", name));
+
+                if src.generated {
+                    attrs.push(("preproc:generated", "true"));
+                }
+
+                if let Some(parent) = src.parent {
+                    attrs.push(("parent", parent));
+                }
+                if let Some(yields) = src.yields {
+                    attrs.push(("yields", yields));
+                }
+                if let Some(desc) = &src.desc {
+                    attrs.push(("desc", &desc));
+                }
+
+                let sym = BytesStart::owned_name(b"preproc:sym".to_vec())
+                    .with_attributes(attrs);
+
+                writer.write_event(Event::Empty(sym))?;
+            }
+            _ => unreachable!("filtered out during sorting"),
+        }
+    }
+
+    writer.write_event(Event::End(BytesEnd::borrowed(b"l:dep")))?;
+
+    // This was not in the original linker, but we need to be able to convey
+    // this information for `standalones` (which has received some logic
+    // from the old linker for the time being).
+    writer
+        .write_event(Event::Start(BytesStart::borrowed_name(b"l:map-from")))?;
+
+    let mut map_froms = HashSet::<&str>::new();
+
+    for map_ident in &sorted.map {
+        match map_ident {
+            Object::Ident(_, _, src) | Object::IdentFragment(_, _, src, _) => {
+                if let Some(froms) = &src.from {
+                    for from in froms {
+                        map_froms.insert(from);
+                    }
+                }
+            }
+
+            _ => unreachable!("filtered out during sorting"),
+        }
+    }
+
+    for from in map_froms {
+        let name: &str = from;
+
+        writer.write_event(Event::Empty(
+            BytesStart::borrowed_name(b"l:from")
+                .with_attributes(vec![("name", name)]),
+        ))?;
+    }
+
+    writer.write_event(Event::End(BytesEnd::borrowed(b"l:map-from")))?;
+    writer
+        .write_event(Event::Start(BytesStart::borrowed_name(b"l:map-exec")))?;
+
+    if sorted.map.len() > 0 {
+        write_fragments(
+            &mut writer,
+            &vec![depgraph
+                .get(depgraph.lookup(interner.intern(":map:___head")).unwrap())
+                .unwrap()],
+        )?;
+        write_fragments(&mut writer, &sorted.map)?;
+        write_fragments(
+            &mut writer,
+            &vec![depgraph
+                .get(depgraph.lookup(interner.intern(":map:___tail")).unwrap())
+                .unwrap()],
+        )?;
+    }
+
+    writer.write_event(Event::End(BytesEnd::borrowed(b"l:map-exec")))?;
+    writer.write_event(Event::Start(BytesStart::borrowed_name(
+        b"l:retmap-exec",
+    )))?;
+
+    if sorted.retmap.len() > 0 {
+        write_fragments(
+            &mut writer,
+            &vec![depgraph
+                .get(
+                    depgraph
+                        .lookup(interner.intern(":retmap:___head"))
+                        .unwrap(),
+                )
+                .unwrap()],
+        )?;
+        write_fragments(&mut writer, &sorted.retmap)?;
+        write_fragments(
+            &mut writer,
+            &vec![depgraph
+                .get(
+                    depgraph
+                        .lookup(interner.intern(":retmap:___tail"))
+                        .unwrap(),
+                )
+                .unwrap()],
+        )?;
+    }
+
+    writer.write_event(Event::End(BytesEnd::borrowed(b"l:retmap-exec")))?;
+    writer.write_event(Event::Start(BytesStart::borrowed_name(b"l:exec")))?;
+
+    write_fragments(&mut writer, &sorted.meta)?;
+    write_fragments(&mut writer, &sorted.worksheet)?;
+    write_fragments(&mut writer, &sorted.params)?;
+    write_fragments(&mut writer, &sorted.types)?;
+    write_fragments(&mut writer, &sorted.funcs)?;
+    write_fragments(&mut writer, &sorted.rater)?;
+
+    writer.write_event(Event::End(BytesEnd::borrowed(b"l:exec")))?;
+    writer.write_event(Event::End(BytesEnd::borrowed(b"package")))?;
+
+    print!("{}", String::from_utf8(writer.into_inner().into_inner())?);
+
+    Ok(())
+}
+
+fn write_fragments<W: Write>(
+    writer: &mut Writer<W>,
+    idents: &ObjectVec,
+) -> Result<(), Box<dyn Error>> {
+    for ident in idents {
+        match ident {
+            Object::IdentFragment(_, _, _, frag) => {
+                writer.write_event(Event::Text(BytesText::from_plain_str(
+                    frag,
+                )))?;
+            }
+            _ => (),
+        }
+    }
+
+    Ok(())
 }
 
 #[cfg(test)]
diff --git a/tamer/src/obj/xmlo/reader.rs b/tamer/src/obj/xmlo/reader.rs
index 1c6b7b90..d53f1892 100644
--- a/tamer/src/obj/xmlo/reader.rs
+++ b/tamer/src/obj/xmlo/reader.rs
@@ -129,7 +129,7 @@
 //! # }
 //! ```
 
-use crate::ir::legacyir::{PackageAttrs, SymAttrs};
+use crate::ir::legacyir::{PackageAttrs, SymAttrs, SymType};
 use crate::sym::{Interner, Symbol};
 #[cfg(test)]
 use mock::MockBytesStart as BytesStart;
@@ -233,6 +233,8 @@ impl<'i, B: BufRead, I: Interner<'i>> XmloReader<'i, B, I> {
     /// ======
     /// - Any of [`XmloError`].
     ///   See private methods for more information.
+    ///
+    /// TODO: Augment failures with context
     pub fn read_event<'a>(&mut self) -> XmloResult<XmloEvent<'i>> {
         let event = self.reader.read_event(&mut self.buffer)?;
 
@@ -278,15 +280,33 @@ impl<'i, B: BufRead, I: Interner<'i>> XmloReader<'i, B, I> {
                 ),
 
                 // `func` symbols include additional data for param
-                // ordering.  We don't care about that, so process the
-                // declaration and then skip the rest.
+                // ordering, which we don't care about.  But `map` includes
+                // source field information which we want to keep.  (We
+                // don't care about `retmap` for our purposes.)
                 b"preproc:sym" => {
-                    let event = Self::process_sym(&ele, self.interner);
+                    let mut event = Self::process_sym(&ele, self.interner)?;
 
-                    self.reader
-                        .read_to_end(ele.name(), &mut self.sub_buffer)?;
+                    match &mut event {
+                        XmloEvent::SymDecl(_, attrs)
+                            if attrs.ty == Some(SymType::Map) =>
+                        {
+                            attrs.from = Some(Self::process_map_from(
+                                self.interner,
+                                &mut self.reader,
+                                &mut self.sub_buffer,
+                            )?);
 
-                    event
+                            Ok(event)
+                        }
+                        _ => {
+                            self.reader.read_to_end(
+                                ele.name(),
+                                &mut self.sub_buffer,
+                            )?;
+
+                            Ok(event)
+                        }
+                    }
                 }
 
                 // Just like the outer match, recurse
@@ -425,6 +445,56 @@ impl<'i, B: BufRead, I: Interner<'i>> XmloReader<'i, B, I> {
             .ok_or(XmloError::UnassociatedSym)
     }
 
+    /// Process `preproc:from` for `preproc:sym[@type="map"]` elements.
+    ///
+    /// Map symbols contain additional information describing source
+    ///   inputs external to the system.
+    ///
+    /// Errors
+    /// ======
+    /// - [`XmloError::InvalidMapFrom`] if `@name` missing or if unexpected
+    ///   data (e.g. elements) are encountered.
+    /// - [`XmloError::XmlError`] on XML parsing failure.
+    fn process_map_from<'a>(
+        interner: &'i I,
+        reader: &mut XmlReader<B>,
+        buffer: &mut Vec<u8>,
+    ) -> XmloResult<Vec<&'i Symbol<'i>>> {
+        let mut froms = Vec::new();
+
+        loop {
+            match reader.read_event(buffer)? {
+                XmlEvent::Empty(ele) if ele.name() == b"preproc:from" => froms
+                    .push(
+                        ele.attributes()
+                            .with_checks(false)
+                            .filter_map(Result::ok)
+                            .find(|attr| attr.key == b"name")
+                            .map_or(
+                                Err(XmloError::InvalidMapFrom(
+                                    "preproc:from/@name missing".into(),
+                                )),
+                                |attr| {
+                                    Ok(unsafe {
+                                        interner
+                                            .intern_utf8_unchecked(&attr.value)
+                                    })
+                                },
+                            )?,
+                    ),
+
+                XmlEvent::End(ele) if ele.name() == b"preproc:sym" => break,
+
+                // Note that whitespace counts as text
+                XmlEvent::Text(_) => (),
+
+                _ => Err(XmloError::InvalidMapFrom("unexpected data".into()))?,
+            };
+        }
+
+        Ok(froms)
+    }
+
     /// Process `preproc:sym-dep` element.
     ///
     /// This represents an adjacency list for a given identifier in the
@@ -638,6 +708,8 @@ pub enum XmloError {
     InvalidDim(String),
     /// A `preproc:sym-dep` element was found, but is missing `@name`.
     UnassociatedSymDep,
+    /// The `preproc:sym[@type="map"]` contains unexpected or invalid data.
+    InvalidMapFrom(String),
     /// Invalid dependency in adjacency list
     ///   (`preproc:sym-dep/preproc:sym-ref`).
     MalformedSymRef(String),
@@ -673,6 +745,9 @@ impl Display for XmloError {
             XmloError::InvalidDim(dim) => {
                 write!(fmt, "invalid preproc:sym/@dim `{}`", dim)
             }
+            XmloError::InvalidMapFrom(msg) => {
+                write!(fmt, "invalid preproc:sym[@type=\"map\"]: {}", msg)
+            }
             XmloError::UnassociatedSymDep => write!(
                 fmt,
                 "unassociated dependency list: preproc:sym-dep/@name missing"
@@ -1282,7 +1357,9 @@ mod test {
             );
         }
 
-        // Some preproc:sym nodes have children (`func` symbols, specifically)
+        // Some preproc:sym nodes have children (`func` symbols,
+        // specifically) that we choose to ignore.  See next test for
+        // data we do care about.
         fn sym_nonempty_element(sut, interner) {
             sut.reader.next_event = Some(Box::new(|_, _| {
                 // Notice Start, not Empty
@@ -1318,6 +1395,146 @@ mod test {
             // next symbol.
             assert_eq!(Some("preproc:sym".into()), sut.reader.read_to_end_name);
         }
+
+        // `map` symbols include information about their source
+        // fields.
+        fn sym_map_from(sut, interner) {
+            sut.reader.next_event = Some(Box::new(|_, event_i| match event_i {
+                // Notice Start, not Empty
+                0 => Ok(XmlEvent::Start(MockBytesStart::new(
+                    b"preproc:sym",
+                    Some(MockAttributes::new(vec![
+                        MockAttribute::new(
+                            b"name", b"sym-map-from",
+                        ),
+                        MockAttribute::new(
+                            b"type", b"map",
+                        ),
+                    ])),
+                ))),
+
+                1 => Ok(XmlEvent::Empty(MockBytesStart::new(
+                    b"preproc:from",
+                    Some(MockAttributes::new(vec![
+                        MockAttribute::new(
+                            b"name", b"from-a",
+                        ),
+                    ])),
+                ))),
+
+                // make sure that whitespace is permitted
+                2 => Ok(XmlEvent::Text(MockBytesText::new(
+                    b"      ",
+                ))),
+
+                3 => Ok(XmlEvent::Empty(MockBytesStart::new(
+                    b"preproc:from",
+                    Some(MockAttributes::new(vec![
+                        MockAttribute::new(
+                            b"name", b"from-b",
+                        ),
+                    ])),
+                ))),
+
+                4 => Ok(XmlEvent::End(MockBytesEnd::new(
+                    b"preproc:sym",
+                ))),
+
+                _ => Err(XmlError::UnexpectedEof(
+                    format!("MockXmlReader out of events: {}", event_i).into(),
+                )),
+            }));
+
+            let result = sut.read_event()?;
+
+            assert_eq!(
+                XmloEvent::SymDecl(
+                    interner.intern("sym-map-from"),
+                    SymAttrs {
+                        ty: Some(SymType::Map),
+                        from: Some(vec![
+                            interner.intern("from-a"),
+                            interner.intern("from-b"),
+                        ]),
+                        ..Default::default()
+                    },
+                ),
+                result
+            );
+
+            // Should _not_ have read to the end.
+            assert_eq!(None, sut.reader.read_to_end_name);
+        }
+
+        fn sym_map_from_missing_name(sut, interner) {
+            sut.reader.next_event = Some(Box::new(|_, event_i| match event_i {
+                // Notice Start, not Empty
+                0 => Ok(XmlEvent::Start(MockBytesStart::new(
+                    b"preproc:sym",
+                    Some(MockAttributes::new(vec![
+                        MockAttribute::new(
+                            b"name", b"sym-map-from-bad",
+                        ),
+                        MockAttribute::new(
+                            b"type", b"map",
+                        ),
+                    ])),
+                ))),
+
+                // missing @name
+                1 => Ok(XmlEvent::Empty(MockBytesStart::new(
+                    b"preproc:from",
+                    Some(MockAttributes::new(vec![])),
+                ))),
+
+                2 => Ok(XmlEvent::End(MockBytesEnd::new(
+                    b"preproc:sym",
+                ))),
+
+                _ => Err(XmlError::UnexpectedEof(
+                    format!("MockXmlReader out of events: {}", event_i).into(),
+                )),
+            }));
+
+            match sut.read_event() {
+                Err(XmloError::InvalidMapFrom(msg)) => {
+                    assert!(msg.contains("preproc:from"))
+                }
+                bad => panic!("expected XmloError: {:?}", bad),
+            }
+        }
+
+        fn sym_map_from_unexpected_data(sut, interner) {
+            sut.reader.next_event = Some(Box::new(|_, event_i| match event_i {
+                // Notice Start, not Empty
+                0 => Ok(XmlEvent::Start(MockBytesStart::new(
+                    b"preproc:sym",
+                    Some(MockAttributes::new(vec![
+                        MockAttribute::new(
+                            b"name", b"sym-map-from-bad",
+                        ),
+                        MockAttribute::new(
+                            b"type", b"map",
+                        ),
+                    ])),
+                ))),
+
+                // garbage
+                1 => Ok(XmlEvent::Empty(MockBytesStart::new(
+                    b"preproc:nonsense",
+                    Some(MockAttributes::new(vec![])),
+                ))),
+
+                _ => Err(XmlError::UnexpectedEof(
+                    format!("MockXmlReader out of events: {}", event_i).into(),
+                )),
+            }));
+
+            match sut.read_event() {
+                Err(XmloError::InvalidMapFrom(_)) => (),
+                bad => panic!("expected XmloError: {:?}", bad),
+            }
+        }
     }
 
     macro_rules! sym_test_reader_event {